If the House of Representatives has its way, Washington's next memorial will honor the 56 signers of the Declaration of Independence, will cost up to $500,000 and "will take an unobtrusive form and serve some functional use if at all possible."

Official, nobody knows what form the memorial will take. It probably will involve some landscaping work and a plaque in Constitution Gardens, the park created last year on the north side on the Reflecting Pool located between the Washington Monument and the Lincoln Memorial.

The House voted 302-3 yesterday to create the new memorial, using profits earned last year by the American Revolution Bicentennial Commission from the public sale of Bicentennial medals. The measure now goes to the Senate for concurrence.

John Rosisvalle of National Capital parks, the arm of the Interior Department that would construct the memorial, said there are no solid ideas as to what form the memorial should take.

Once the congressional resolution is enacted, the Interior Department will advertise for and select a landscape architect to prepare plans.

The project design must be reviewed by the Fine Arts Commission, which has given preliminary support to the proposal. J. Carter Brown, commission chairman, said the body prefers a "subtle addition" to Constitution Gardens, perhaps "something no more complex than a simple plaque."

The House Administration Committee, which sent the measure to the House floor, called for the unobstrusive and functional features. "Because of the large number of statues and memorial structures in the Washington, D.C., area, concern has been expressed that the memorial not add to the list," it said in its formal report to the House.

The three opposition votes were cast by Reps. Gary Myers (R-Pa.), Tom Corcoran (R-111.) and William F. Goodling (R-Pa.). Although they did not explain their reasons, all three have reputations as fiscal conservatives.