The Moroccan made eleven appearances for the club this season, after van Dijk picked up a knee injury ruling the star out for the rest of the campaign.
RKC offered the 27-year-old a new three-year deal to stay at the club, but it was rejected for not matching the players demands.
It was thought that the former SC Heerenveen man had been stalling signing a new deal as he was seeking assurances from coach Martin Jol over his status at the club.
Van Dijk is expected to reclaim back the number one jersey at the Mandemakers Stadium upon recovering from knee ligament damage.
