Riat was named to Switzerland's under-20 team for the 2016 IIHF World Junior Championships in Helsinki, Finland. He played 6 games with the team, putting up 2 goals and 2 assists. Riat also made the team for the 2017 IIHF World Junior Championships in Montreal, Quebec, Canada. He appeared in 5 games and scored 1 goal and 5 assists.