Organizers of the United States Football League, a professional league that will play its games in the spring and will include a franchise in Washington, formally will announce today that its teams will begin playing next March.

The Washington team will be owned by Berl Bernhard, a prominent local attorney, and minority partners. It is expected to play its games at RFK Stadium, although it hasn't signed a lease yet with the D.C. Armory Board.

"We have agreed that they could rent RFK, but the exact terms will be negotiated in the future," said Robert Sigholtz, the armory's general manager.

The USFL, brainchild of New Orleans businessman David Dixon, will have franchises in at least 12 cities, including New York, Chicago, Philadelphia, Los Angeles, Boston, Detroit, Birmingham, Tampa Bay and San Francisco. Teams will play a 20-game season, with a championship game July 4.

At a press conference today in New York, organizers also are expected to announce that Chet Simmons, now president of the ESPN cable sports network, will be the league's first commissioner.

The league will have a draft based on regional territories. Owners have been required to post $1.5 million letters of credit and have been told to expect losses of $1 million the first year and up to $4 million the first three years, until the USFL can get contracts with cable television networks.

Bernhard, 52, a member of the law firm of Verner, Liipfert, Bernhard and McPherson, was director of the U.S. Commission on Civil Rights under President John Kennedy.