A citizens' advisory committee is recommending that the Arlington County Board authorize a $40 million Metrorail bond referendum this November to help meet Arlington's share of the cost of building the 101-mile subway system.

In a report to be discussed at a board work session next Saturday, the board-appointed committee said it had concluded that a referendum was the best option. Board Chairman Ellen M. Bozman said yesterday that the board is not likely to act on the recommendation until Aug. 13 when it will decide what bond issues, if any, to place on the November ballot.

The board could decide on a smaller Metrorail bond amount. Arlington voters rejected a proposed $25 million Metrorail bond issue in 1975. But board Vice Chairman John G. Milliken, Arlington's representative on the Metro board, said yesterday, "I think people support Metro and will support a bond issue if they are convinced the money is needed and will be prudently spent."

The citizens' committee--which includes past Democratic County Board chairman Joseph S. Wholey and former Republican chairman Stephen H. Detwiler--noted that Metro says Arlington's total obligation to rail construction is currently $64.3 million.

After state aid of $5.4 million is deducted from that share, Arlington owes $58.9 million, or $18.9 million more than the recommended $40 million bond issue would provide. Another $7.5 million in state aid is expected during the next five years, leaving Arlington's currently projected debt at $11.4 million if the referendum is passed. The committee is recommending that the additional debt be paid out of pay-as-you-go capital, either from the general fund or additional state aid.

Anton S. Gardner, director of the county's department of management and finance, said the proposed $40 million bond issue would cover the county's obligations through 1988. Arlington, which has nine of its 10 planned Metro stations open, has traditionally paid 10 percent of the local governments' share for construction. Its share is scheduled to increase to 12.4 percent over the next few years, then taper to nothing in 1990.