The vapor-liquid coexistence boundaries of fluids which interact with an isotropic square well potential, in addition to highly directional patchy interactions are evaluated using grand canonical Monte Carlo simulations combined with the histogram reweighting and finite size scaling methods. Our results show that at a constant total areal density of patches, the critical temperature and the critical density increase monotonically with an increasing number of patches. The vapor-liquid coexistence curve plotted in reduced coordinates (i.e., the temperature and the density scaled by their resepctive critical values) are found to be effectively independent of the number of patches. These results have implications for the phase behavior of model protein and colloid solutions.