Track star Renaldo Nehemiah has signed a professional football contract, moving from No. 1 in the world to No. 83 for the San Francisco 49ers.

With 49ers Coach Bill Walsh sitting to his right and agent Ron Stanko to his left, Nehemiah, 23, said today, "There's nothing else for me to do in track. I just wanted to be the best in the world. I was that. Now, it's time to move on."

Nehemiah, who hasn't played football since high school, when he was an option quarterback in Scotch Plains, N.J., six years ago, signed a four-year contract, with the first year guaranteed. He also received an estimated $75,000 to $100,000 signing bonus. It is believed his annual salary will be in the same range.

"We put a lot of importance into the guarantee," Stanko said. "It's common knowledge that Renaldo made six figures in track and field."

Walsh said of the player who received the only guaranteed contract the 49ers ever have given, "There isn't any reason for us to think he can't make it." Nehemiah's position will be wide receiver.

In all, there were eight National Football League teams pursuing Nehemiah, who set the world record in the 110-meter high hurdles in 12.93 seconds last year. The teams were San Francisco, Washington, Philadelphia, Dallas, New England, San Diego, Oakland and Pittsburgh.

Redskins General Manager Bobby Beathard admitted "we wanted Nehemiah badly." Beathard also said he was not pleased with Stanko's handling of negotiations.

"He (Stanko) told us that Nehemiah wanted to play here close to his home in Gaithersburg. We made a big mistake. We made an offer in good faith. Then the guy (Stanko) shopped around our offer after he said he wouldn't do it. Money was the only consideration."

"We never gave any team another team's figures," Stanko said. "We were concerned with ethics. One reason Skeets didn't go to Washington was a week passed between the time Bobby Beathard asked us what it would take to sign Skeets and when he came back and said he couldn't afford it . . . The financial difference between the 49ers and the Redskins was incredible."

Beathard said the Redskins "couldn't come close to what the 49ers offered."

Nehemiah said his final choice was between Washington and San Francisco. The 5-foot-11, 177-pound former University of Maryland track star admitted it finally came down to one thing: the money.

"The Redskins made me a sound offer," he said. "But the difference between the offers wasn't like the difference between $1 and $3. It was more like the difference between $1 and $15."

Nehemiah said he realized that once he had signed his contract he could not compete in the Olympics. A spokesman for the Athletics Congress said today Nehemiah could ask for reinstatement to compete in track, but would not be allowed in Olympic competition under existing rules.

"I've been the best runner in the world for four years," Nehemiah said. "I've won every race one could win. If I had lost the Olympics in 1984, there's no way you could tell me I wasn't the best hurdler in the world. 1980 was my year. I would have won the Games.

"In the last four or five weeks, with my tryouts for football, I've gotten more exposure than I did during four years as the best runner in the world. I don't want to have to go to Europe to be appreciated."

Frank Costello, Nehemiah's former track coach at Maryland, said when contacted, "The only thing that puzzles me is why now? It's a shocker to me. Most track people are sorry to see this. It's a tremendous gamble on Skeets' part."

Nehemiah, a television-radio major at Maryland who has television aspirations, pulled away for a moment from his third television interview in five minutes and said, "I gave up something that was a guarantee: track. Please don't compare me to other track people who have failed in football. I'm not a failure until Coach Walsh tells me I am."