After the season, Kosti gave up his final two years of eligibility and signed a professional contract with the Calgary Flames. He began the next season with the Moncton Golden Flames but ended up appearing in only 15 games during the season. He joined the Canadian national team in 1986 and played the next two years with the program, becoming the team's 3rd goaltender at the 1988 Winter Olympics because he didn't dress for any of the games he's sometimes left off of the roster. Kosti came close to appearing in an NHL game in November of that season. Regular starter Mike Vernon had taken a hard shot off the mask and was held out for precautionary reasons. Kosti was called up and served as a backup on the 21st against the Pittsburgh Penguins but rode the bench the entire game. When Vernon was cleared for the following match, Kosti was returned to the national team. After the Olympics, Kosti finished out the season with the Salt Lake Golden Eagles. After his entry-level deal with the Flames expired in 1988, it was not renewed and he wasn't invited to the team's training camp. Kosti retired as a player and began pursuing a career in business.