 In 2001 Seip signed for Eredivisie club SC Heerenveen, making his debut in the 2002–03 season and went on to make six league appearances that season, as Heerenveen finished in seventh place, qualifying for the 2003 UEFA Intertoto Cup.Seip played in all five of the club's games in the Intertoto Cup, as they reached the finals, where they lost to Spanish La Liga side Villarreal.In 2003–04, he made 31 league appearances and scored one goal as Heerenveen finished in fourth place, qualifying for the 2004–05 UEFA Cup.