The Reagan administration's top personnel official now says that reductions-in-force have been a disruptive and costly way to cut government spending and trim the size of the federal work force.

While still committed to the use of RIFs to curb government costs, Donald J. Devine, director of the Office of Personnel Management, has begun to draw up new regulations he says would lessen the disruptive impact of the RIFs and allow agencies to run them more efficiently. Some of his ideas are not expected to be any more popular with U.S. workers than was the decision to RIF.

Devine, who often has argued that current RIF guidelines pose severe management problems, soon will propose revised RIF procedures that would emphasize job performance over seniority in deciding whom to lay off and would set limits on the ability of RIFfed workers to take the lower grade jobs of others.

Democrats in Congress have maintained that there are better ways than RIFs to reduce the federal work force -- among them attrition -- and have proposed legislation to protect federal workers from losing their jobs. Devine wants to improve this cost-cutting tool, not do away with it.

Asked to assess the RIF process at a recent House committee hearing, Devine said: "I will be the first to admit that it is inefficient." Testifying during D.C. Del. Walter E. Fauntroy's oversight hearings into the impact of RIFs on the Washington area, he characterized RIF procedures as "complex, sometimes inequitable, and cumbersome." And he agreed with an internal OPM memorandum that said that the use of RIFs is not cost-effective in most cases.

In an interview with editors and reporters of The Washington Post last week, Devine said he plans to propose reforms aimed at curbing problems in the RIF procedures that he said are hurting morale and proving costly.

A spokesman for OPM said this week that the agency "is leaning toward" adopting RIF guidelines that would rearrange the order under which federal workers are given special bonus points that help protect them against dismissal. Disabled veterans and veterans in general still would be ranked at the top, but seniority, which now ranks third as a criterion for retention, would take on less importance than job performance. The spokesman said OPM hopes shortly to institute a more meaningful employe evaluation system that would give job performance ratings "real substance."

The new regulations, which the agency wants to implement in time to govern new RIFs in the fiscal year that begins Oct. 1, also would limit the notice procedures required in advance of a RIF. The intent here is to avoid what has become the common practice of issuing a general RIF alert that scares hundreds of employes when only a few actually will lose their jobs.

Rep. Patricia Schroeder (D-Colo.) has introduced a bill that would give federal workers the option of voluntarily taking payless furloughs to save their jobs. Fauntroy has sponsored a bill to combat the effects of the RIFs by giving displaced workers first crack at any future government openings.

In addition, the Federal Government Service Task Force headed by Rep. Michael D. Barnes (D-Md.) now is drafting legislation that would require federal workers and managers to explore other cost-saving measures.

Since the start of Reagan's term 16 months ago, nearly 9,000 government workers, about 2,300 from the Washington area, have been dismissed from their jobs. More than three times that many employes have been moved into new or lower grade jobs and duties as a result of complicated "bumping" and "retreating" rights they hold under Civil Service regulations.

The job "retention rights," as they are called, often have worked in a way that has put top-level executives into the typing pool and thrown longtime program experts into fields they know little about. Federal unions defend the seniority and retention rights provisions in the RIF procedures, arguing that RIFs never were intended to be used on such a wide scale as that employed by the Reagan administration.

An internal OPM memo making many of the same points was cited by Fauntroy during his recent hearing. The memo, prepared earlier this year when OPM was about to conduct its own RIFs, was highly critical of the entire process.

As "a rule of thumb," the memo argued, RIFs displace three to four workers from their jobs for every employe actually dismissed. The chain reaction they set off hurts organizational efficiency, destroys morale and adversely affects agency "missions." RIF-incurred costs, such as severance pay and unemployment compensation, could end up being so expensive that OPM, as an example, would have to "fire more than twice as many people as we need to in order to make the dollar savings."

The memo further suggested that OPM was not following its own recommendations that agencies explore other cost-saving alternatives before deciding to RIF workers.

Although Devine is taking the lead in proposing changes in RIF procedures, other officials say it is no secret that news reports of seemingly illogical job reassignments following a RIF have proved embarrassing to the administration. Even Republicans, especially those who represent large groups of federal workers, have blanched at some of the results.

Rep. Marjorie Holt (R-Md.), quizzing Devine at the Fauntroy hearings, said OPM should have considered the consequences and made changes before "we get into all of this turbulence and chaos that we have now."