The Fairfax County School Board has chosen a second consultant to help it find a replacement for Superintendent William J. Burkholder and has announced it will make a major effort to involve county residents in the search.

The board has scheduled a special meeting for Oct. 29 at which citizens who are not members of county organizations can suggest the qualifications they believe the next superintendent should possess. Civic groups will address the board the following night. Both meetings will begin at 8 p.m. in the auditorium of Luther Jackson Intermediate School on Gallows Road.

Burkholder, 55, announced last month that he would resign after criticism erupted over a proposed four-year extension of his contract. The contract would have given him an annual salary of $79,450 and a yearly cash payment of $77,800 to compensate for continued loss of his high early retirement benefits.

The second consultant is John Brubacher, head of the education administration department at the University of Connecticut. He will work with Carrol F. Johnson of the National School Boards Association, a consultant the School Board selected two weeks ago. Johnson, a former school superintendent in White Plains, N.Y., and a professor of education administration at Columbia University, specializes in superintendent searches.

Brubacher and Johnson will be paid a total of $15,000 to compile a report that should help the board evaluate the 100 applicants who are expected to seek the job, a school spokesman said yesterday.

The School Board is expected to to announce its choice by March 1. The deadline for applications is Dec. 10.

Jay D. Jacobs, an assistant Fairfax superintendent, said he has mailed 1,100 recruiting letters in the last month "to everybody who would know anybody who is qualified for this position." The mailing has included letters to major colleges, to superintendents and school board chairmen of large school districts, and to school administration associations in 50 states. "We are giving this the broadest national perspective that I think you can give a search," he said.