Four members of the Washington Capitals left yesterday to play in the World Ice Hockey Championships in Czechoslovakia.

Joining Team Canada were goaltender Pat Riggin and defensemen Scott Stevens and Larry Murphy. Defenseman Timo Blomqvist will play for Finland.

Team USA, an 11-1 loser to the Soviet Union in its opener Wednesday, invited defenseman Rod Langway and center Bob Carpenter, but both declined. The U.S. and Canada meet Saturday.

Eleven Capitals have participated in international play this season. Besides the new quartet, seven played in the Canada Cup -- Mike Gartner for Canada, Bengt Gustafsson and Peter Andersson for Sweden and Langway, Carpenter, Dave Christian and Bryan Erickson for the U.S.

The Capitals have signed goaltender Alain Raymond of Trois-Rivieres to a professional contract and are reported close to an agreement with another highly regarded Quebec League draftee, defenseman Yves Beaudoin of Shawinigan. The team also plans to sign Jim Thomson, a right wing for the Toronto Marlboros who is currently playing with Binghamton.

Defenseman Paul Cavallini of Providence College, a 1984 draftee with impressive credentials, is considering joining the Canadian Olympic team, which would keep him out of the Capitals' reach until 1988.

Capital Centre already is embarked on a program to enlarge the rest room facilities. Complaints were widespread following the Capitals' playoffs, when fans standing in the long lines missed Washington's overtime goals and/or all three goals the Capitals scored in slightly more than two minutes.

The Capitals' Binghamton farm club swept its first-round playoff from Springfield, the New York Islanders' farm, in four games. Binghamton next meets the winner of the Baltimore-Rochester series.