With Ajax playing PSV Eindhoven today, AZ knew a victory would increase the pressure on the current league leaders.
RKC initially frustrated the hosts and they had a great chances to take the lead which Richard van der Venne and Emil Hansson both failed to take.
In the 29th minute, though, AZ had the lead when Oussama Idrissi cut in from the left before sending a low strike into the net. Seven minutes later, Myron Boadu slotted in a Jonas Svensson cross to make it 2-0.
Six minutes into the second half, Idrissi found the top corner with an excellent strike from outside the box to make it 3-0 before Calvin Stengs added a fourth with a deflected effort.
The victory moves AZ level on points with Ajax at the top, while RKC remains bottom of the table.