Sheila Patton, a vice president at the Hill & Knowlton public-relations firm, is to be named Nancy Reagan's press secretary, according to sources close to her and the Reagan tansition staff.

"Mrs. Reagan called me today," said the 38-year-old Patton from her Falls Church home last night. Patton's appointment is to be announced today by the Reagan transition office.

Patton has been with Hill & Knowlton for four years -- three here, and one at the firm's Houston office. Prior to that, she worked as the public-relations manager at the Colorado National Bank in Denver and before that, at the Pittsburgh office of Burson-Marsteller, another public-relations firm. She graduated with a degree in journalism from Duquesne University in Pittsburgh.

A Washington native, she grew up in Falls Church.

"We realized that we needed somebody with Washington experience," said a Reagan source. This was a reference to the dismissal of Robin Orr, the Oakland Tribune society columnist who was Nancy Reagan's press secretary for 28 days -- a time period in which several embarrassing gaffs attributed to the first lady appeared in print.

"We were looking for a competent, professional person," confirmed the Reagan source, "not someone who was looking for notoriety for herself." Patton, the source said, "will be a team player."

Patton was interviewed by Nancy Reagan during the future first lady's mid-December trip to Washington. It was one of more than a dozen interviews she and staffers have conducted in the wide search for press secretary, a position that was given to Orr on Nov. 15. She was relieved of her duties Dec. 13.

Patton, who has two children and is divorced, is described as businesslike but open, with "good ideas" about the job.

Patton, who skis, plays tennis and works needlepoint, will receive a salary in the $38,000 range. Her present boss is Robert Gray, head of the Washington office of Hill & Knowlton and also co-chairman of Reagan's inaugural committee.