While still in college, Rast was selected as a member of the U.S. U-20 national team at the 1989 U-20 World Cup. In that tournament, the U.S. took fourth place. Not only did Rast go to two NCAA championship games and take fourth in the U-20 World Cup, he also won a gold medal as a member of the U.S. soccer team at the 1991 Pan American Games. He then capped his career as a youth international as the captain of the U.S. soccer team at the 1992 Summer Olympics. This team did not experience the same level of success, going 1–1–1 and failed to qualify for the second round. The following year, he was part of the U.S. team at the 1993 World University Games.