The first time the Washington Capitals summoned Bill Riley from Dayton, in December, 1974, he waited until 11 p.m. to call his wife in Nove Scotia, because the telephone rates were cheaper. He might as well have delayed a while longer, because his NHL "trial" lasted just one game.

This season Riley received an honest, 10-game look and what general manager Max McNab saw was sufficent to win a professional contract for the 26-year-old right wing. For a few months, at least, Riley will be able to pick up the phone without checking the time.

During his tryout, Riley collected only one goal and one assist, but he played well defensively and lifted the team emotionally with his aggressiveness.

"Looking at the games down the stretch here, I think it's going to get a little mean," McNab said after today's signing at Capital Centre. "We are past the stage of catching anyone off guard. Riley can handle himself physically. He is in a sense a (Bob Kelly of Phildadlphia), able to come off the bench and do a good job, stir things up.

"He has shown us good corner work and he plays the man as he should. It's not any strange coincidence that our goals against are down. Continually rubbing out guys makes the difference. The guy Riley goes against doens't skate faster in the third period. Historically, that has been a problem."

During Riley's 10 tryout games, prior to tonight's contest here aginst the Sabres, the Capitals had yielded only 26 goals, fewest of any NHL team over that stretch.

"He's a fine young man," McNab added," our type of guy. He's a winner and a team man. He has good hockey ability. His passing is good and he makes few mistakes really. The tempo here should help him build up his skills."

Riley did not play junior hockey. He was skating at the senior amateur level while toiling as a welder in an aluminum smelter when Washington scout Lou Jankowski discovered him in remote Kitimat, British Columbia.

Accepting the challenge of that first Washington camp, Riley was dispatched to the International League farm at Dayton, where he raised more eyebrows with his fists (279 penalty minutes) than with his scoring (12 goals).

One of hockey's few blacks. Riley quietly endured the taunts of bigoted fans - in Toledo they asked whethe he sat in the back of the bus or sharpened his teammates' skates, and they called him things he had not heard as a boy in Canada.

Riley took nothing from anyone on the ice, however, and his penalty total climbed to 301 minutes last year ebefore his tormentors decided they were losing the battle.

Riley's goal production reached 35, stirring new interest in Washington. When replacements for injured Capitals proved ineffectivie in December, the call went out for Riley and now he is free of the bus leagues, front or back.

Blair Stewart, who suffered a broken right leg Nov. 7 and had been playing in Springfield for the last two weeks, rejoined the team here. That boosted the active roster to 20 and prompted speculation that left wing Mike Marson would be returned to the American League team.