A Catholic relief coordinator and a Georgetown University doctor are in Bangkok this week to study how contributions can best be put to work there and study the idea of sending Georgetown medical students to help Cambodia's starving millions.

If their services can be put to use, the students, who are in their final year, may be in Cambodia by December, according to George Wagner, co-ordinator for the Cambodia relief effort of the U.S. Catholic Conference Migration and Refugee Services.

In response to President Carter's request that Americans contribute to the Cambodian relief effort through their churches and synagogues, religious groups here and across the nation have launched extensive fund-raising campaigns.

Roman Catholic dioceses already have contributed more than $500,000 following requests by Catholic bishops for special Sunday collections. That figure is expected to grow rapidly as more dioceses hold their collections.

Contributions from $10 to $1,000 have been pouring into Catholic relief agencies from individuals of all religious backgrounds, according to Wagner.

THE U.S. Catholic Conference here is taking the names of volunteers interested in serving in Cambodia -- but it is particularly interested in nurses and doctors. So far, about a dozen persons have volunteered, in addition to the Georgetown University group.

Conference officials, said they also have received dozens of calls from persons offering to adopt Cambodian orphans. But relief agencies said they cannot make any adoption plans until they determine if children are orphans or simploy separated from their parents.

Most other religious organizations are taking special collections for Cambodia between now and Christmas.

The Church World Service relief agency of the Protestant-Orthodox National Council of Churches expects to surpass its $5 million goal for CAMBODIAN RELIEF, ACCORDING TO EXECUTIVE DIRECTOR paul McCleary. It received 200,000 in the first two weeks of the appeal.

It is receiving pledges and cash donations daily from Protestant churches across the country. Some of the larger pledges have come from the United Methodist Church, which has promised $2 million, and the Church of the Brethren, which has pledged $100,000, according to McCleary.

The U.S. Conference for the World Council of Churches is attempting to raise $2.5 million before the end of the year. Approximately $500,000 of that money will come from Church World Service, which will deduct the amount from its $5 million fund-raising campaign.

The American Jewish Joint Distribution Committee has contributed $12,000 to interdenominational relief groups. According to Herbert Klatzik, executive vice president of the committee, the figure is low because the group launched its campaign only two weeks ago.

According to Church World Service, American religious groups have pledged over $100 million for the estimated 2 million to 3 million starving Cambodians.

The State Department estimates that $111.3 million is needed to buy and deliver the 165,000 toms of supplies that it says will keep the Cambodians alive for another six months.

That figure already has been surpassed, according to State Department calculations that show a dozen countries already have pledged $137 million for Cambodian relief. President Carter has promised that the U.S. will supply $69 million of that amount.

Catholic Relief Services organized an intensive campaign in June to feed and clothe the Cambodian refugees fleeing to Thailand. Since that time, they have dispatched 25 convoys carrying 1,100 tons of emergency supplies to the Cambodian border.

They have been operating refugee camps in Thailand since 1977 and in the past several months have established several centers for displaced persons there and soup kitchens.

Following are some of the organizations that are accepting contributions for the Cambodia relief effort. Envelopes should be marked "Cambodia Emergency Fund."

U.S. Committee for UNICEF, 331 East 38th St., New York, 10016.

American Red Cross, 2025 E St. NW, Washington, 20005.

Catholic Relief Services, 1011 First Ave., New York, 10022.

Church World Service, 475 Riverside Dr., New York, 10027.

International Rescue Committee, 386 Park Ave. South, New York, 10016.

Oxfam America, 302 Columbus Ave., Boston, 02116.

American Friends Service Committee, 1501 Cherry St., Philadelphia, 19102.

CARE, 660 First Ave., New York, 10016.

Lutheran World Relief, 360 Park Ave. South, New York, 10010.

American Jewish Joint Distribution Committee, 60 East 42nd St., New York, 10017.

Interfaith Hunger Appeal, Box 5055, FDR Station, New York, 10022.