Rainsberger served as the head football coach at NAIA-level Washburn University from 1962 to 1964, posting a record of 17–10 and winning a conference championship in 1964. His record at Washburn ranks him ninth in terms of total wins and tenth in terms of winning percentage. He became the 11th head football coach at Southern Illinois University Carbondale for one season in 1966, tallying a record of 4–5–1. Rainsberger returned to his alma mater to serve as head football coach at Kansas State from 1975 to 1977. He started his tenure there while, winning his first three games, but ultimately compiled a record of 6–27. Rainsberger left Kansas State with the program placed on probation for giving too many scholarships.