It's dizzying schedule, even for a campaign veteran. Nine countries in as many days - and snow in Warsaw, spring-like weather in New Delhi, heat in Saudi Arabia, winter in Teheran and Paris. Throw in the unblinking stare of the world press and the slippery demands of protocol, and one might reasonably wonder how, clothes-wise, Rosalynn Carter's surviving.

The answer appears to be that she's doing it her way - an quite nicely.

Her clothes, all by American designers, are attractive, functional and in what most people would consider a moderate price range. Favorites are worn again and again at public functions, a pattern Mrs. Carter set during her first year in the White House. It was little surprise to regular Carter-watchers when a cornflower-blue, empire-style dress purchased for the inaugural a year ago turned up again at last Friday's state dinner for the Carters in Poland.

In the Carter style, too, say White House aides, the practice allows the First Lady to travel relatively light - exact number of suitcases unknown or at least unrevealed.

Neither is there anyone along on the trip to assist Mrs. Carter in a valet capacity, though it's doubtful that the wife of the President of the United States is left to do her own laundry by her host at each stop on the itinerary.

At home, Mrs. Carter is known to give little time to shopping and even less to fashion chit-chat. Lately her clothes have been selected for her by Georgia Young of Lewis & Thomas Saltz, the Washington retailer. Young asks designers to submit clothes or sketches with fabric swatches for the First Lady to consider.

At least one cape-coat (beige tweed) by Ilie Wacs was purchased specifically for the current trip and pin-stripe suit and tie blouse, new from the Jerry Silverman summer collection, surfaced in New Delhi on Tuesday when the Carters paid their respects at the Mahatma Gandhi memborial.

Designer Dominic Rompollo's corn-flower-blue dress and another in "Rosalynn green" are among the hold-overs from a year ago.

Judged from afar, the strategy so far seems to serve Mrs. Carter well. Even ceremonial boots at the Gandhi memorial failed to ruffle her look. And when jets, helicopters, motor-cades and other presidential paraphernalia threaten her attempts to look her best, she's not above the practical approach. Standing in freezing rain and snow last Friday in Warsaw, Mrs. Carter wrapped a scarf over her hair and around her neck and clamly shut out the cold.