Running back Mike Rozier, the second-leading rusher in the U.S. Football League, has agreed to a four-year contract with the National Football League's Houston Oilers and will join them soon, his agent said yesterday.

Meanwhile, there are indications that another USFL star, wide receiver Trumaine Johnson, also might jump to the NFL. He sat out the USFL season because of a contract dispute with the Arizona Outlaws, but now says he is "close" to signing with the San Diego Chargers.

He would not confirm or deny reports that he will buy out his contract with the Outlaws. The Chargers declined comment yesterday.

Art Wilkinson, Rozier's agent, said that the former Heisman Trophy winner who played for the Jacksonville Bulls this season will earn $1.7 million over four years with Houston, or $425,000 per season. Rozier, 24, did not appear at a news conference Wilkinson held in Philadelphia yesterday.

General Manager Ladd Herzeg of the Oilers would not comment on the terms of the agreement with Rozier, who rushed for 1,361 yards and scored 11 touchdowns for Jacksonville (9-9), which did not make the playoffs.

However, Oilers spokesman Bob Hyde said, "We will be making arrangements in the very near future to have Mr. Rozier come to Houston and take a physical and we don't anticipate any problems with that. After he completes the physical, the contract will be signed."

Early yesterday, the Oilers deferred any announcement until the NFL office had reviewed his contract situation. Later in the day, Dick Maxwell, an NFL spokesman, said, "Our legal counsel, Jay Moyer, informed the Oilers this afternoon that, based on our review of the . . . situation, he is now free from any contract obligations to the USFL or any of its member clubs."

Maxwell said that Rozier could not have been signed by the Oilers until Aug. 1, unless he had satisfied the league's demand that he prove he is free of contractual obligations.

Nick Kish, the Bulls' director of player personnel, said that Rozier signed a one-year contract with the Bulls before this season and is now contractually free. "I think if Mike has been offered the money that Art Wilkinson claims the Houston Oilers have offered him, then it's a prohibitive amount for us," Kish said.

"But Wilkinson has given us three different figures, $2.2 million, $2.4 million and $2.7 million over four years. I think only John Riggins and Walter Payton make that much money in the NFL. I guess it's a case of take the money and run."

Kish said that Jacksonville has made no firm offer to Rozier for next season, when the USFL plans to move to the fall. Kish said that Bulls owner Fred Bullard has shown Rozier real estate that might be included in a contract with the Bulls.

"We're going through a period with a negative cash flow for the next 10 months or so," Kish said, looking toward the USFL fall schedule in 1986. "We'll have no TV revenues or ticket revenues from this point forward. That's a lot of money Wilkinson is talking about. Mike is looking at a situation where he can make a double dip, earn his salary from us this year and from Houston."

After setting rushing records at the University of Nebraska, Rozier signed with the now-defunct Pittsburgh Maulers of the USFL. He rushed 792 yards for the Maulers last season.

The NFL held a supplemental draft last June, in which teams drafted rights to USFL players. Houston selected Rozier with the second pick in that draft.