The Redskins signed veteran Jim Kiick yesterday to shore up the battered and undermanned running back position.

A spot on the roster was opened when defensive end Dennis Johnson was placed on injured reserve, Johnson partially tore the medical collateral ligament in his left knee Sunday against the Cowboys and will be in a cast at least three weeks.

Kiick was signed because, according to coach George Allen, "We needed another running back badly," The 31-year-old Kiick is Allen's late-season insurance policy.

Starting fullback Clarence Harmon is limping on a sprained ankle and reserve fullback Eddie Moss has a calf injury that prevented him from practicing yesterday during a 2 1/2-hour closed workout.

Fullback John Riggins, still recovering from torn knee ligaments, apparently is not going to be ready to play, if at all, until at least the final game of the regular season against the Rams.

Kiick once teamed with larry Csonka in that powerful Miami Dolphins backfield that helped win Super Bowls 7 and 8. Kiick played out his option with the Dolphins in the 1974 season and signed to play with Memphis of the old World Football League in a much ballyhooed package deal with his pal Csonka and receiver Paul Warfield. When WFL Folded Klick signed a Denver and played with the Broncos in 1976 and for eight games this season.

He was released by the Broncos Nov. 8 and "was the best back available," according to Allen.

He will be used mostly at fullback the rest of the season, Allen said. Kiick is 5-foot-11, 205 pounds and carried a 3.8-yard rushing average into the 1977 season after six years in the NFL.

In Miami, he was also a fine pass receiver. In his first four years in the league he caught 44, 29, 42, and 40 passes and gained more than 1,000 yeards each of those years in combined rushing and receiving.

This season was not particularly pleasant for Kiick. He was released by the Broncos three different occasions. Twice Denver reclaimed him.

Kiick carried the bail only once for one year and caught two passes for 14 yards as the Broncos played rookie Rob Lytle ahead of him.

'I've been in Miami the last few weeks just resting," Kiick said after his first Redskin practice yesterday. "I don't know what happened in Denver. I guess I just didn't fit into their plans. I thought I played well in the preseason. I know I did.

"I don't know what's going to happen here. I'm here for three games and that's as far as I'm looking. We'll just see how things go from there."

Allen said he was pleased with Kiick's performance after one practice. "I thought he looked good. He's retained a lot of his quickness and he made very few mistakes. There were two or three backs available. But I wanted somebody who had done it (played in important games) because these (last three) games are so important.

"I think he can help us, "Allen said adding that Kiick might well see some action Sunday when the Redskins play the Bills in Buffalo.

"I really don't know," Riggins admitted yesterday when asked if he thought he could play again this season. "If I wanted to be a hero, I could go play and tear it up worse than it is now. There's no new development; it just takes time, that's all, if I wanted to heal the way it's supposed to heal.

"It's just a day-to-day thing. My leg is still weak. I'm just lifting weights now. I still can't run on it, but I'm going to start doing some swimming. Yes, if I do too much, you're darned right there's pain."

Special-teamer Dallas Hickman broke a thumb in the Dallas game and will be fitted with a cast. But he is listed as probable for Sunday's game.