HARVARDEDGE  PRINCETON QUARTERBACK: Quarterback Brian White, who needs just 125 yards to become the fifth-leading passer in Harvard history, has improved as the season has progressed. But the two-year starter's completion percentage is still only .427. A week ago he only went to the air 15 times, but that probably will change this week. Knows Multiflex well. Can run and throw. Has thrown three touchdowns on the year.    QUARTERBACK: Senior Doug Butler, the alltime leading passer in Ivy League history and one of the finer signalcallers in the entire country, totes his act into town today. The holder of virtually every offensive record at Princeton, Butler will provide the Crimson with its biggest test of the year. A week ago, he threw for 438 yards on 34 completions in 59 attempts. RUNNING BACKS: The squad's best area a year ago, it has struggled this year. Had its best day of the year last week, rushing for 296 yards in a 17-7 victory over Dartmouth. The leader--and probably the best runner in the Ivy League--is senior fullback Robert Santiago. The All-Ivy runner has picked up 320 yards this year, and needs just over 400 more to become the fifth leading rusher in Harvard history. The loss of junior halfback Rufus Jones to a knee injury has hurt this group, but junior George Sorbara filled in with his best game ever last week. Joe Pusateri is the other starter.    RUNNING BACKS: Fullback Butch Climmons leads in rushing and no one else has more than 100 yards. Climmons has rushed 63 times for 221 yards and two touchdowns. But with the Tigers now using the Wing-T offense, also expect halfbacks Steve Foster (23-88-ITD), Craig Fitchett (28-99-ITD), and Chris Ratliff (17-43-ITD) to get the ball. Princeton has averaged just around three yards per carry this year, so don't be surprised if Butler opens up the passing game like he did last week against Colgate, despite the newly installed Wing-T. RECEIVERS: Sophomore LaMont Greer won the starting split end job two weeks ago, and he's been impressive ever since. Greer is second on the squad in receptions with seven. A week ago he had two touchdowns called back because of penalties. Has blazing speed, as does Santiago. Santiago, who has hauled in 13 receptions for 162 yards, is the team's leading receiver.  Even  RECEIVERS: Superstar split end Derek Graham is gone, and that's good news for opposing secondaries. But in his place are Climmons, who's been on the receiving end of 18 catches for 199 yards, and Foster, who's grabbed 16 receptions for 200 yards and one touchdown. Split end Tom Uruquhart leads the wide outs with 10 catches for 150 yards. This group is talented and experienced. Lots of speed. OFFENSIVE LINE: The squad's weakest area, this group hasn't given the Crimson runners the holes they enjoyed a year ago. Nevertheless, it's still improving and has shown progress. The leader of this unit, which will have its hands full with the Princeton defensive line, is senior left tackle George Kostakos. Main problem here is lack of size and lack of depth. Will need to give White time to throw today, if Harvard is to win.  Even  OFFENSIVE LINE: An experienced offensive line is one of the main reasons Princeton Coach Ron Rogerson switched to the Wing-T offense this year, though that move has drawn a bit of fire from those who'd like to see Butler throw on every down. Comprised of three seniors and two juniors, the offensive line is one of the squad's bright spots, though it hasn't opened holes for the Tiger runners like Rogerson thought it would. DEFENSIVE LINE: One of Harvard's most improved units, the defensive line that includes Bill Ross, K.C. Smith and Jerry Garvey last week held Dartmouth to only 52 yards rushing. The Crimson has recorded 18 sacks, with Smith recording five of those just last week. Princeton's Wing-T is much like the Multiflex that the Crimson sees everyday in practice, and that should help. Will have to get to Butler, if Harvard wants a low-scoring contest.  Even  DEFENSIVE LINE: The Tigers boast one of the most underrated defenses in the entire league. Overall, Princeton has picked up 19 turnovers, including six fumbles. Defensive tackle Jim Petrucci has recorded five sacks and could give the Crimson trouble today. Of note is the fact that Princeton has allowed only six points in the third quarter but has been outscored, 38-12, in the final 15 minutes of all its games this year. One reason? Not enough depth on the defensive line. LINEBACKERS: Senior linebacker Brent Wilkinson leads Harvard in tackling with 47 and last week the Crimson captain picked up his first two sacks of the season. This is one of the Crimson's top areas, with Scott Collins and Bob Joyce providing more than adequate support for Wilkinson. Will have to cover Princeton's receivers out of the backfield today, and that could be a potential problem.    LINEBACKERS: Middle linebacker Anthony DiTommaso leads the Tigers in tackling. But after that the Princeton linebacking crew has been somewhat spotty. Had trouble last week against Colgate, which scored 49 points against the Tigers mainly by picking on this group. Senior Lorne Keller and junior Matt Heisler round out this unit, which is not exceptionally quick. DEFENSIVE SECONDARY: This is the area many consider Harvard's best. Led by senior safety Cecil Cox, who has picked off four passes, the Harvard defensive secondary will get its biggest test of the year today. So far this season, this extremely aggressive unit hasn't been burned. In particular, Lee Oldenburg has been a pleasant surprise. In all, the Crimson has picked off 10 passes, just two less than the 12 it picked off all of last year.    DEFENSIVE SECONDARY: An extremely aggressive group, the Tigers have picked off 13 interceptions this season to lead the Ivy League. Eleven of those steals have come from defensive backs. Safety Joe Harvey is the leader here, having picked off three passes. Though outshined by the Harvard defensive secondary, this group probably will provide a good test for Crimson quarterback Brian White. KICKING GAME: Senior Rob Steinberg has been more than adequate on his kickoffs, field goals and extra points. Only problem area has been his erratic punting.  Even  KICKING GAME: Sophomore placekicker Rob Goodwin has been a pleasant surprise, while junior Rob DiGiacomo has been as erratic as Steinberg with his punting.