Bob Margarita, freshman football coach since 1951, resigned yesterday to accept the post of backfield coach under Boston University's new head coach, Steve Sinko. The move came as no great surprise, since it had been remored in the Boston press for the past few weeks.

The former star halfback at Brown first came to Harvard in 1946, when he served as backfield assistant under Dick Harlow, then head varsity coach. In 1948 he went to Yale as backfield coach. The following year he moved to Georgetown, where he served as head coach until Georgetown abandoned football. He then returned to Harvard as freshman football coach.

Margarita is known to have had considerable support for the position of head coach, left vacant by the firing of Lloyd Jordan, but filled yesterday with the appointment of John Yovicsin. However, it is believed that Margarita expressed his disinterest in the position.