Ray Cline, an executive director of the Georgetown University Center for Strategic and International Studies as well as a former CIA station chief in Taiwan, is enthusiastic for causes he supports.

He is so enthusiastic about Taiwan and its political virtues that he is, at the same time and from the same offices, running a university study program and a political campaign on behalf of "Free China" -- a latter-day China Lobby.

Cline's activities as a simultaneous scholar and lobbyist have been organized in a complicated and careful way, which insulates him from charges of impropriety.

And, as none of his campaigns get money through the Taiwan government, he is not registered as a foreign agent. But, as he says, when one is as involved as he is, "There's not an easy way to draw the line."

Cline and the Georgetown Center are, he emphasizes, integral parts of Georgetown University. As such, he has launced university study projects on Taiwan, partly paid for by a $97,000 grant from a group of prominent Tawian businessmen.

He also organizes free trips to Taiwan for congressional aides under his university "Pacific Basin Project."

At the same time, Cline, with some of his own CSIS staff and relatives, working out of the same Georgetown University offices, is running his new pressure group for Taiwan interests, the Coalition for Aisan Peace and Security (CAPS)."

Cline also helps run, out of the same offices, the Committee for a Free China, once a prominent part of the old China Lobby, which made the State Department tremble in the 1950s.

His assistants in these enterprises include Cline's son-in-law, Roger Fontaine, a CSIS fellow who in private life is a Reagan policy adviser and a friend of Peter Hannaford, a close Reagan aide. Hannaford's public relations firm, Hannaford & Deaver, is a paid lobbyist for the Taiwan government.

Cline is another member of the Georgetown CSIS group who is expected to be influential with Reagan. Originally a supporter of the George Bush campaign, he is now submitting papers to Reagan on subjects including Taiwan.

Although Taiwan supporters have lost their major battles, culminating in what Reagan described as "outright betrayal" in the 1978 agreement between the United States and Peking, they now lobby for weapon sales to Taiwan, for better access to U.S. officials by the Taiwan government and against dissidents with Taiwan.

The Georgtown University CSIS, funded by big foundations and business corporations, describes itself as a "nonpartisan and nonprofit" self-financing research institution, which exists "to foster scholarship and public awareness."

Last year, cline's department cleared with the Senate Ethics Committee the first of two trips for Capitol Hill staff members to Taiwan, both paid for out of an educational study program, and those who went had no qualms accepting.

As G. Grayson Fowler, one of the aides of Sen. Edward Zorinsky (D-Neb.), points out: "If an invitation came from a group supporting Free China, I might have had some problems."

Geryld Christianson, an aide to Sen. Claiborne Pell (D-R.I.), said, however, that it would have made no difference to his acceptance had he known of the organizers' specific sympathies: "I knew very well they were very pro-Republican China." But the trip was scrupulously organized, allowing the guests to meet anyone they liked, including dissidents. "We knew it was going to be put together with the idea of giving us as favorable an impression as possible."

Cline says: "There's no direct tie between the Taiwan money and the congressional visits." Instead, he says, the free trips are financed out of other, general funds, while the Taiwan money keeps staff and research going.

The Taiwan money is provided by a Taiwanese business magnate, Chen Fu Koo, and the association of businessmen he chairs. They have contributed $50,000 and have promised a second installment of $47,000.

On the first trip, in 1979, the CSIS also paid for Cline's son-in-law, Roger Foutaine, to accompany the congressional tour. Foutaine is a Latin-American specialist, but he says: "I have an interest in other things."

On the second week-long trip, in May 1979, the CSIS paid for Robert Downen to accompany the guests. Downen is a CSIS fellow on Cline's staff, and former aid to Sen. Bob Dole (R-Kan.).

He published a scholarly book for CSIS entitled "Taiwan Pawn in the China Game" in 1979, and edits "Asia Report," a montly CSIS newsletter.

Meanwhile, behind an office suite at 1015 18th St. NW in Washington that says "Georgetown University" on the door, two rather diferent operations are going on.

One is CAPS, president Ray Cline, director Robert Downen and unpaid voluntary help Judith Fontaine, Cline's daughter and Roger Fontaine's wife. Downen puts out a bulletin lambasting the State Department.

It attacks "the unpredictable and often antagonistic attitude of our State Department officials in their efforts to curry favor with the Chinese Communist regime." It also calls for the sale of advanced jet fighters and sophisticated Harpoon missiles to Taiwan.

CAPS is applying for tax-exempt status as an educational and literary organization. Its statement of aims as a nonprofit corporation says that should any threat to the independence and freedom of Taiwan be found to exist: "It shall be the responsibility of the directors . . . to bring such threat to the attention of Congress and the American people."

Cline says he rents space from the university as a matter of convenience, and CAPS has "no money, no personnel, but a lot of high-powered advisors." He adds "In order to avoid any suggestion the university was lobbying, I felt that CAPS was an enterprise that ought to be set up separately."

Downen says: "The suite that we use over here is half paid for by the Georgetown University Center, and half by private funding from CAPS. That some comes from private funding by individuals, which is totally U.S.-originated." The China Committee, he says, rents space from CAPS. u

"Ray Cline and I happen to wear two hats. None of our projects overlap," he says.

Cline says his junior is mistaken about the finances of the enterprises. "Any expenses specifically for the coalition have been coming out of my personal funds."

CAPS had provided space which Cline allowed the Committee for Free China to use free of charge. "They're broke. I pay the rent myself."

Cline has also become a vice president of the China Committee, whose veteran campaigner, Walter Judd, has retired. Ann K. Martin, listed on letterheads as executive director, whom Cline describes as a secretary, is housed in the office suite at 1015 18th St. NW.

Cline's wife, Marjorie, has an office in the main CSIS building with her name on the door and a listing in the internal directory. But she does not help Cline with his Taiwan work, he says. "She's not on the payroll or the roster. She is a professional editor who just takes care of my publishing and teaching schedule."

Marjorie Cline accompanied Cline on a recent visit to Taiwan, but, like his work on behalf of CAPS and the Free China Committee, this was done, Cline says, without any Taiwan funding, government or private.

"Asia is a hobby of mine," he says.

"The key is your own academic capability and credentials and integrity," he says. "Maybe you have a purist idea of what an academic life should be."