RONNIE REAGAN has a great job, and he can go to any Redskin game he likes. Marion Barry has a pretty good job, and he gets to park his mayoral limousine right there by the VIP entrance at RFK Stadium. But Randy Clark has the best job in our town: He gets to watch all the Redskin home games from the line of scrimmage, and they pay him.

If you attend or watch Redskin home games you've seen Randy Clark thousands of times, and you'll see him maybe a hundred times more during Sunday's playoff game against the Chicago Bears at RFK Stadium. Clark's the guy who holds the down marker, which shows where the ball is to be put in play, and how many more chances the offensive team has to make a first down.

It seems a simple enough assignment and it is, Clark says, "except that each head linesman has his own rhythm and style, and you have to remember to do it his way every time. If I'm doing my job right, it's one less thing he has to worry about."

The main strain is trying not to get too involved in the game. "Man, you're right there on the field, with the sweat flying and the pads popping and people screaming like crazy, and when the Skins make a great play, or something goes really wrong, it's hard not to show emotion. I'm a fan, all five of us on the sidelines crew are fans, and keeping your feelings bottled up like that just whips you."

But he does keep the cork in it, because while the home crew is employed by the Redskins, "during the game we're working only for the NFL," Clark says, "and showing favoritism is the NFL's Number One No-No."

Clark also has to keep his lip buttoned, although hardly anyone else does. "You should hear it down there," he says. "They all do it. For instance, you'd think from watching on television that Don Shula (coach of the Miami Dolphins) is calm and controlled, but I have heard him get off on the officials, I mean he'll say the magic word and a whole lot more. I don't know how the officials stand it, but they do. I've got great respect for them, they've got one of the toughest jobs there is."

But Clark, as we were saying, has one of the greatest jobs there is, and he's always hearing the footsteps of people who think they could do it better. "There's somebody on my case all the time," he said. "They write, they call. And I've lost friends because I wouldn't let them have the job for 'just one game'."

Eat your heart out. Clark has held the job for 11 years, working every down of every home game except for one Sunday when he was in the hospital having his back checked out. It checked out fine, and he hopes to surpass his father before him, who got the job through a friend who was a friend of the George Preston Marshall family, then owners of the team. Dad Clark worked the sidelines for 25 years, in Griffith Stadium and D.C. cum RFK Stadium before handing the job down to his son, along with the pair of season tickets that goes with the job.

That is to say that the Clarks, man and boy, have been on the homer crew since 1948, and Randy Clark, who's only 37 now, plans to carry on well into the 21st century. After that, well, "I've got a couple of daughters coming along."

In real life, Clark's a Montgomery County police officer assigned to the school safety division, which he likes because he likes kids -- he coaches youth sports -- and which also gives him Sundays off. He recruited three of his fellow officers to the sidelines crew: Dave Barnes, who keeps track of when, where, against and by whom penalties are called; Rich Marshall, who tends the clip that marks the nearest yardline on the 10-yard chain and is assistant timekeeper; and Ron Frew, who minds the chains along with the fifth crew membMike Ingrao, a union organizer.

Clark sees every game twice, from the sidelines and then at home on his video recorder, "and it's like watching two different games," he says. "There's an awful lot you miss from ground level. On the other hand, there's so much you can't experience from the stands or on television, mainly the intensity of the players.

"I know it's a business and they get paid to play, but those guys are there to win, and not just for the money. Once the game gets going, the players are in a different zone. Maybe on another planet."

But the key to any Redskin game is equally apparent from sidelines, stands or tube, Clark says: "Joe Theismann. If he's sharp -- and you can usually tell from the first few plays -- we've pretty much got it made. If Joe's having a bad day, anybody can beat us."

It's heady to be so intimately associated with a team making a bid for its third straight Super Bowl, but Clark has paid his dues. There have been times -- whole seasons, in fact, and not so very long ago -- when Washington was one of the sad sacks of the NFL. Hard times may come again, but "I'll be suiting up every Sunday for as long as I can," Clark says.