In the Grace Episcopal Church, Barbara Scott Welles, daughter of Mrs. Ricard Riggs Ohrstrom of Old Whitewood and Edward Kenneth Welles of Roscoe, Ill., became the bride of Stig Toft Rasmussen, son of Mr. and Mrs. Knud Toft Rasmussen of Scottsdale, Ariz. The ceremony was performed last Saturday evening by the Rev. G. Charles Rowe and a reception followed at Old Whitewood.

Carrying a cascade of gardenias, the bride wore a peau de soie wedding gown and a Spanish lace veil, an heirloom of her godmother, Mrs. Richard N. Calhoun of Stamford, Conn. Jenifer Tener of Middleburg, Va. was maid of honor and the groom's brother, Alan T. Rasmussen of Phoenix, Ariz., the best man.

Mrs. Rasmussen made her debut in 1969 at the New York Infirmary Ball. She is an alumna of Mt. Vernon College spending her junior year in Switzerland at the Grenoble University with studies in Paris as well. The bride attended the University of Arizona and holds a BFA from the University of Montana. Her father, previously associated with Besly Welles Corp., is now involve in security systems.Her grandparents are Mrs. Edward K. Welles of Lake Forest, Ill. and the late Mr. Welles, a prominent business and civic leader, the late Mrs. Margaret Williamson Hoyt of Warrenton, Va. and the late William Henry Hoyt, an historian and lawyer of Greenwich, Conn.

Mr. Rasmussen has ridden in nationally ranked horse shows throughout the country and was an assistant trainer with a well-known New York trainer of thoroughbred racehorses. He is currently an assistant trainer for Stephen DiMauro at Belmont Park. His father is a construction engineer in Arizona.

The couple will honeymoon in Jamaica and spend the winter in Santa Anita, Calif. before returning to Elmont, N.Y.