RPA is strongly NP-hard even for squares, therefore there is no fully polynomial time approximation scheme (FPTAS) for this problem, unless P=NP. The previously best result is a (1/2-epsilon)-approximation by Jansen & Zhang for our problem. We present a polynomial time approximation scheme (PTAS) for this problem, i.e. a family of algorithms which compute for any accuracy epsilon>0 in polynomial time a solution with ratio (1-epsilon).