Guitarist-singer Kenny Rankin has quietly made his mark

Remember what is sometimes affectionately referred to as ''the great folk music scare'' of the '60s? Every hidey-hole had a singing guitarist then, but where have they all gone?

Today, it seems that, if you don't have an eight-piece band with an entourage of backup singers, or wear strange clothes and sing through a synthesizer, you're odd man out on the pop scene.

But then there's Kenny Rankin. Rankin, a native New Yorker transplanted to Los Angeles, has been singing and playing his guitar in clubs and concert halls for 20 years, offering his own natural blend of pop, folk, soft rock, jazz, blues, and Brazilian-Latin music. His wide repertoire ranges from Beatles tunes through old standards like ''When Sonny Gets Blue,'' to Brazilian bossa novas, to old R&B numbers - and he writes original songs which display a musical sophistication that belies his lack of formal training.

''I don't read music,'' he told me recently; ''I never took a lesson. But I know what I hear.''

As far as notes and chord symbols are concerned, ''they're hieroglyphics.''

With a great ear and an ability to rework existing material into something fresh, Rankin has quietly made his mark, putting out four albums on the Little David label, as well as two on Mercury and one on Atlantic, and winning the respect of some top names in the business.

Both Carmen McRae and Mel Torme recorded one of Rankin's early songs, ''Pardon Me,'' a jazz waltz with an engaging lyric (McRae even named her album after it) - before Rankin had a chance to record it himself.

One hears something of Torme in Rankin's voice and style, and his remarkable range extends gracefully into the upper reaches without ever sounding like a forced falsetto. In fact, he does much of his singing in his higher range, which sounds uncannily like a trumpet, especially when he swings into his own percussive, Latin-influenced vocalese.

Rankin can be counted on to sing any given song in a way it hasn't been done before. But he never gets so far away from the original concept that he leaves his audience behind in the dust. If a song has a beautiful melody, it will still have a beautiful melody when he's through with it. He manages to pull off his melodic meanderings with the utmost harmonic accuracy and respect for the original.

Asked whether he has focused particular attention on creating this approach to the music, he said he hasn't:

''I haven't worked at anything. I'm really a nonworker. My plan is no plan - the best thing that has happened to me has just happened. I'm really lazy.''

He is hardly what one could call an electrifying stage presence. At Mardi's, where he recently performed and to which he is scheduled to return June 2, he simply sang his songs, with a minimum of dry-witted commentary in between.

''I can't play to people,'' he admits. ''I can look over their heads and talk to them, but . . . .''

So whom does he play for?

''Me.''

So it's the music alone that draws his followers into his spell - no gimmicks. And that's why Rankin feels he's being overlooked by the pop recording industry.

''I haven't shaved my head or painted my feet green, so they're not selling me as a commodity.''

Then he mused:

''I feel grateful for the gift that I have. I know I haven't cultivated it as much as I could have, or maybe should have, but I didn't, so, I don't know . . . .

''I'm singing now better than I ever have before, with a lot of confidence and understanding - it comes from time.''

And to accomplish what he has accomplished - to keep an audience riveted to their seats for an hour with just a guitar and a voice - is no simple task.

''I try not to think of that too much - it's kind of overwhelming!''

Kenny Rankin will will also appear at Charlie's in Georgetown, Washington, D.C., May 25 through 30.