Frk represented the Czech Republic at the 2011 World Junior Ice Hockey Championships and 2011 IIHF World U18 Championships. At the U20 WJC, Frk led all players in the tournament with 31 penalty minutes and was the seventh-place Czech team's second-leading scorer with three goals and three assists in six games. Frk and Dmitri Jaškin were the leading scorers for the Czechs at the U18 WJC with five points each. Frk scored one goal and four assists as the Czechs finished eighth.