Like Willem said, the "official" Ronde van Nederland is cobbled together from six separate long distance routes (the LF routes). The best map of it I could find on the interweb is
this one. The route is the thick red line but as you can see you can lengthen it or shorten it at as you see fit.
There is a booklet on the route that costs about GBP 15. It includes more maps, hotel/camp site addresses, descriptions, history, etc. than you can shake a pump at but it's only in Dutch. There is also (are at least there used to be) a map of the Netherlands showing all the LF routes so you can piece together your own tour.