I wanted to amend the below to say that "The NCAA selection board for at-large teams does in fact begin with at-large candidates in the Top 75 RPI plus conference regular season champions."
Teams with RPI ranks above 75 have made the NCAA Tournament as at-large teams. These were all conference champions.

Originally Posted by
GoneGolfin
_ This is certainly not the case. The NCAA selection board for at-large teams does in fact begin with at-large candidates in the Top 75 RPI only. But the RPI is also used extensively throughout the selection process ... everything from national seed selection before at-large bids are awarded to selecting the last few at-large teams. I remember one year where the national seeds were the RPI teams ranked 1->8 save one team that was #9.
RPI needs to be taken out and shot.
Brian _