Susan Rapp, a 17-year-old senior at Edison High School in Alexandria, Va., finished in a tie for seventh place in the 100-meter breaststroke at the United States Swimming Championship trials tonight.

Rapp, who tied Michelle Merchant from Cincinnati's Pepsi Marlin Club, was timed in 1 minute 14.15 seconds in the final. Kim Rhodenbaugh, also with Pepsi Marlin, won the event in 1:11.04.

Rapp was timed in 1:13.46 in the preliminaries. That was less than two seconds behind the fastest qualifier, Jeanne Childs, who set an American record in the 200 breaststroke Tuesday. She finished in 1:11.51.

Susan's older sister Betsy, 22, was the 20th qualifier in the 100-meter butterfly at 1:04.07. World record holder Mary T. Meagher was the top qualifier in the event at 59.92, and later won the final in 59.44.

Sherri Hanna, who swims for Stanford and trains at Starlit in Fairfax, Va., in the summer, was timed in 8:44.82 in the preliminary heat for the 800-meter freestyle. Hanna will swim in the championship final Friday night (she qualified by finishing sixth) and will get her second chance to gain a place on the United States team. She finished fifth in the 400-meter freestyle Wednesday.