Montgomery County Council President Elizabeth Scull has endorsed William G. Colman, a former school board member, for the council seat that will become vacant Tuesday when Norman Christeller resigns.

The council charter specifies that the post must be filled within 30 days, a replacement is expected to be named sooner because the council's intensive work on the new operating budget starts March 1.

Scull said the person who replaces Christeller should be able to take on the council workload without "missing a beat." Colman, a retired federal government employee who was once executive assistant to the director of the National Science Foundation, is "calm and fair and has the right personality for a council member in this difficult year," Scull said. She noted that Colman's experience with the Montgomery County school budget would make him an able replacement for Christeller, who reviewed the sizeable school budget every year.

The council already has 24 candidates; 20 are residents who applied for the vacancy when Christeller announced last March he would resign. Those 20 persons still are considered eligible for the post.

Several candidates have been active in Montgomery County politics, civic activities or local government. Although Christeller and councilman Dickran Hovespian, who announced this month that he will not seek another term, have noted the frustrations of the demanding schedule of a council member, some candidates still said they found the job appealing.

"All the things I've done over the past six years are related to local government," said candidate Sally P. Kanchuger, a seven-year memberof the League of Women Voters in Montgomery County. Kanchuger cited League studies she has done on the county and some of its agencies and noted that she has directed the League's County Council Observers, citizens who are assigned to go to council meetings during the week.

"It's the center of action," said Kanchuger. "Everything that involves the county goes through the council."

Kanchuger is also president of the West Montgomery Citizens Association and one of several citizens who run the Committee to Save Our Land.

Another candidate, Mable Granke, who is a member of the Montgomery County Planning Board, said her experience with the budget process and master plans for zoning in communities qualify her for the council job. Granke ran unsuccessfully for the council in 1974.

Two candidates said their experience with budget analysis is an important factor in their decisions to seek the council post.

"One of the problems the county has been facing is a budgetary analysis," said Bruce D. Patner, a lawyer. "That's one of my main interests."

"I've looked at a number of the budgets in detail," said retired Labor Department economist Sigmund Berkman. As current chairman of the council's fiscal advisory committee, a citizen task force, Berkman and the committee advise council members on various aspects of the budget each year. Berkman is the husband of Vera Berkman, the chairman of the Washington Suburban Sanitary Commission.

All candidates who submitted resumes by the Jan. 27 deadline will be interviewed by the council in the next few weeks. The council then will appoint the new member. Because the Christeller is a Democrat, all candidates to replace him must be Democrats registered in Montgomery County. No district representation is required because Christeller is an at-large councilman.