A Department of Transportation task force voted unanimously yesterday to adopt the central provisions of a proposal to develop a $143 million rail line that would link the Metro system to Dulles International Airport.

Although the plan, which would replace traditional federal subsidies with private capital, has strong support from the Reagan administration, officials in Northern Virginia have expressed concern that local taxpayers would have to shoulder burdens the federal government has assumed in the past.

"There is no question that our work now is to convince localities that this plan makes sense for them," said Chris A. Christopher, a member of the DOT-appointed task force composed of Northern Virginia residents. "The easy part is over. Now, we have to sell it to the public."

The feasibility study was requested by Rep. Frank R. Wolf (R-Va.) after several organizations expressed interest in building a high-speed rail to run along the 16-mile strip in the center of the federally owned Dulles Access Road.

Wolf said yesterday that he had not yet seen the report and would not comment on its recommendations until he had. But he added that he had long supported the idea of a rail to Dulles, and that the explosive growth of the region around the airport would make it more important in the coming years.

"I just hope people will look at this concept with an open mind," he said. "Some mornings, driving to work from Fairfax County can be a grim, grim experience. I think we owe it to ourselves to look at other options."

The proposal recommends a rail system that would stop at six places between Dulles and West Falls Church, where an Orange Line Metro station is scheduled to open next summer.

According to the study, prepared for the Urban Mass Transportation Administration by the Rice Center, a nonprofit educational corporation affiliated with Rice University in Houston, most passengers on the rail line would be commuters, with only about 15 percent riding to and from the airport.

Under the proposal, the rail system would pay for itself through fares, increased tax assessments for property along the route, a tax on passengers at the airport and perhaps an increase in the levies on the Dulles Toll Road.