Carol Kane was a finalist for the Best Actress Oscar when she was 22. Janet Gaynor is the only other actress who was nominated for the award as such a youngster.

Four years later, Kane is still excited by the memory of Oscar night, even though she didn't win (for "Hester Street") and even though the people who saw her after the ceremony "came up to me like someone died. I swear to God, they made me feel like a major tragedy had happened."

Her nomination led to a voting membership in the Academy, and some of this year's nominees are friends of hers. Over breakfast at a Capitol Hill cafe known for the scowls of its staff, Kane predicted that "Bob" [DeNiro], "Meryl" [Streep] and "Chris" [Walken] will win in a "Deer Hunter" sweep.

But Kane is a long way from Hollywood. As the Oscar show opens tomorrow, she'll be opening at the Folger Theatre in "Benefit of a Doubt," playing a 14-year-old retarded girl in Appalachia.

It's not that she hasn't been able to get jobs in the movies and television. She has been in "Carnal Knowledge," "The Last Detail," "Dog Day Afternoon," "Annie Hall," "The World's Greatest Lover" and plenty of PBS dramas. She's in three movies that will be out soon: "The Muppet Movie," "The Mafu Cage" and "When a Stranger Calls."

She was in a Dr. Pepper commercial, which took her to Rome and Switzerland for two weeks on a budget as big as the one for the feature-length "Hester Street." The commercial was hardly ever aired.

But lately, for the first time since she was 6, she has begun to doubt the wisdom of her career choice.

She recited a description of the stages of an actor's life she has heard: "First it's 'Who's Jack Smith?' Then 'Get me Jack Smith.' Then 'Get me a Jack Smith type.' Then 'Who's Jack Smith?' I'm teetering in between three of those plateaus, depending on who you speak to.

"This is a grueling profession. Either you can't get work, or you can't get certain kinds of parts, or you get a part and it kills you because it's not good enough, or you get successful and feel guilty about it.

"There are directors who don't cast you for the way you act but for the way you are, the way you behave around the dinner table. This isn't disturbing when you get hired; but there are times when you don't get hired, after spending all this time honing your ability to embody many different characters because they look at you as a person and don't see what they want."

Kane had vowed never to play another adolescent. But she was packing for a flight to California from her New York home recently when "Benefit of a Doubt" director Barnet Kellman, a friend of Kane's, called and asked her to step into "Benefit." The actress originally cast in the role had bowed out to take a movie role. Kane took a script on the airplane with her, and "unfortunately I loved it," despite the character's age.

Of playwright Edward Clinton's creation, she says: "He writes in a way that people really talk. They don't necessarily talk in whole sentences. One thing doesn't always follow another. Things come out of nowhere from the back of your mind. You don't feel you have to work to hold the words up."

She also liked her role. The character "has something all actors wish to have-a total lack of censorship. If you ask her if she likes you and she doesn't, she'll say no." Kane has not researched the problems of the retarded in order to prepare for the role. "I've found out how old she is for me emotionally, which is much younger than 14. I went through that age [in Cleveland, no less] and what I've done is try to get back there."

Kane's last performance in Washington was at the White House. She was in "Out of Our Father's House," a show about women in American history that was produced in New York and brought to the White House last spring for a meeting of Senate wives hosted by Rosalynn Carter.

The cast behaved "like kids, running around, taking pictures. We were dressed in period costumes, and all the furniture was old, so we really looked like we belonged there."

She met President Carter, who "said he watches me in movies all the time. I said I watched him on TV all the time. He said, 'I bet you say that to all the presidents.'"

The president said he had just seen her in a movie. She guessed the titles of several movies of hers that might have been in release in Washington at the time, but no, it was "the one with the sailors," he said. "The Last Detail." He explained that he could see just about any movie he wanted, whenever he wanted to see it.

"He's great," said Kane, smiling in a way that expanded her already angelic features until she looked absolutely seraphic.

It sounds almost as exciting as the Oscars. But Kane hasn't completely forgotten Lotus Land. She cast her Academy ballot. It wasn't necessary to see all the movies, she explained: "You can just close your eyes" and, she demonstrated, point at the ballot in order to select your choices.

During the opening-night party tomorrow, a TV set will broadcast the Oscars from the Folger stage. Kane and company want to know if Bob and Meryl and Chris win. CAPTION: Picture, Carol Kane at the Folger Theater: She is still excited by the memory of her Oscar night in Hollywood when she was 22. By Douglas Chevalier-The Washington Post