Twelve supporters of the Equal Rights Amendment yesterday adopted the uniform of the suffragists -- and their protest tactics -- to mark the 60th anniversary of the day women got the right to vote.

Instead of chaining themselves to the White House fence, the women chained themselves to a railing outside the offices of the Republican National Committee on Capitol Hill. And instead of burning the speeches of President Woodrow Wilson, they burned a copy of the platform the Republicans passed at their convention in July.

"The fact that the Republicans withdrew support of the ERA from their platform is a scandal," said Rev. Betty Bone Schiess, an Episcopal priest, who described herself as a former Republican turned "lukewarm Democrat."

"We are here to show our deep commitment to the ERA," said Sonia Johnson, a Mormon who was excommunicated because she criticized church leaders' opposition to the ERA. "We have to escalate this battle. We are ready to make personal sacrifices."

Johnson and the 11 other women, dressed in white dresses with purple sashes, were backed up by a group of about 50 supporters who marched and sang. They carried banners reading, "Will the Party That Freed the Slaves Become the Party that Enslaves Women?" "How Long Must Women Wait for Liberty?" and "Did Men Get Equal Rights State-By-State?"

They sang old suffragist protest songs and some not-so-old protest songs, including "We Shall Overcome" and "We Shall Not Be Moved." In the latter song, they included the names of old heroines like Alice Paul, who wrote the first draft of a bill to guarantee women equal rights, and new heroines like Mary Crisp, who stepped down as vice chairman of the RNC in July with an emotional speech criticizing the party for changing its stance on the ERA.

At its convention, the party adopted a platform that said it supported equal rights for women, but it stopped short of making its traditional endorsement of the ERA. The amendment has been approved by 35 state legislatures, but needs three more by June 1982.

The 12 women said yesterday they were prepared to go to jail for their cause, but no one was arrested. D.C. and Capitol police stood by, but Deputy D.C. Police Chief Robert Klotz said that since no one in the building had filed a complaint and there were other doors available, the women could remain outside as long as they wished.

A spokesman for the RNC said the committee had no plans to have the women arrested.

At one point during the protest, several of the supporters blocked other entrances to the office building, but they moved when asked to do so by the police.

About seven supporters blocked the entrance to the Capitol Hill Club next door to the committee offices. Several persons stepped over the protesters to enter the building. The seven protesters moved after the organizers complained that they were drawing attention away from the 12 women chained outside the offices.

Several passers-by cheered the protesters, while others shook their heads in disgust. "This is ridiculous," said Phil Guarino, the white-haired director of a senior citizens group that works out of the same building as the RNC.

"I think they are probably picketing the wrong place," said a nattily dressed man in a blue pinstriped suit. "They should have been at the convention."

The protesters were unmoved. Johnson said yesterday's protest was "a signal" that the ERA supporters have moved into "a new stage."