A check-in point in the lobby of Rockefeller Center awaited the 800 buyers and press arriving for today's Geoffrey Beene show. Then came another checkpoint for seat assignments outside the studio where the collection for next fall would be shown. "It's like immigration," laughed Bernie Ozer, executive with the large buying office of Associated Merchandise Corp.

Indeed, the scene matched the arrival of a superjet at Dulles International Airport. But in terms of the clothes, they were strictly all-American and distinctly Geoffrey Beene, characteristically uncluttered and free-flowing in exquisite fabrics. And in a season when most of the collections--particularly Yves Saint Laurent, Karl Lagerfeld and Azzedine Alai a--have strong ties to their European colleagues, a collection independent of French-designer influence is a rare and welcome thing. No wonder the audience gave Beene a standing ovation at the end of the show.

Beene throws his customers a curve for fall. There isn't a straight line in the collection. Shoulders are rounded and so are sleeves. Wavy lines are underscored with trapunto and regular quilting; belts, applique's and even some hemlines have rounded edges. It is a change from Beene's former T-shape clothing, taking off the hard edges and adding a softness to the clothes.

Unlike the rest of the designers, Beene sticks to the colors of minerals, a relief from the strident shades popular this season. "It is not a good time for bright colors. They are unrealistic and jarring," he said before the show.

Beene likes clothes short--many are above the knee. On some of the tallest models they appeared particularly short, but will be made longer in the stores. "Short clothes are freer," said Beene, who showed longer lengths as well.

But long or short, daytime or evening, everything is done with an eye to easy care and easy packing. A bantamweight wool dress is reversible and so are several of the coats; one evening coat with quilted satin applique' reverses to different color applique'. Wool coats, suits and even evening clothes can be rolled up and stuffed in a suitcase.

It is hard to tell just what are some of Beene's fabrics from a few feet away, but up close a textured wool turns out to be woven in West Africa; a shimmery dress is Lurex quilted velvet; others are satin cloque', coupe de velours, embroidery or sequins. The quilted applique' on the shoulders of a coat develops into a winged shape when the model turns and shows the back.

Unlike Beene's work, there was no difficulty identifying the beading and embroidery used by Oscar de la Renta for fall during his show today at the Parsons School auditorium. They are always bold and elaborate and sometimes look like jewel-encrusted belts on velvet skirts, or jewelry on dresses when they are really sewn on.

De la Renta left a rack of clothes behind in his showroom today. The rack was filled with the full-printed challis skirts he designed for fall and then abandoned in favor of a sharper, cleaner line. An example was the three-quarter flared coat in sapphire-blue, lined with black, over a short, narrow black skirt. There are swinging skirts, but rather than the fullness starting at the waist as before, they are gored so they flare out from the hem.

But de la Renta's strong suit is evening wear. While some of the long dresses are unadorned, his faithful followers will no doubt go for the beaded variety. There's one that looks like Miss America with a beaded sash (or was it inspired by Queen Victoria sitting on her throne these days at the Metropolitan Museum?) Others are bedecked with ribbons and medals embroidered on velvet. Just the thing when the invitation says, "White tie and decorations."