The 17-year-old youth accused of hitting cowboy movie star Roy Rogers in the face with a pie last month pleaded guilty yesterday to a charge of disorderly conduct in the incident and was fined $100 by a Fairfax County Juvenile and Domestic Relations Court Judge.

The youth, who is attending high school and working part-time as a machinist, told Judge Thomas Fortkort that "he realized it was a stupid thing to do and he didn't intend to harm Roy Rogers," according to a court official present during the 15-minute trial.

Juveniles are entitled to a private trial and the youth said he did not want reporters present during the hearing.

"The kid expressed concern about his actions," the court official said. "He sounded like the incident was completely out of character."

Forkort acted the "potential seriousness of his actions and the mistaking of his intentions," the official said.

The youth said after the hearing he hand no comment.

THe incident occurred while Rogers, 65, and his Sons of the Pioneers singers were performing Aug. 30 at the Roy Rogers Family Restaurant in Fairfax City. The youth ran past the bandstand and hurled a cottage cheese pie in Rogers' face.

"Let me got a punch at him," Rogers yelled. "I hope they stuff a Roy Rogers hamburger down his throat."

Then Rogers blurted into one of the live microphones "Lemme at that son of a bitch."

Rogers wiped his face, and continued his show singing and talking about Rog Rogers roast beef sandwiches and God.