We make use of a one-dimensional mean-field model formulated in previous work to determine the effects of added submonolayer amounts of surfactant during growth on a vicinal surface. We assume that the surfactant acts to increase the activation barrier for surface diffusion and examine the consequences of this relative to average island size and island density for varying surfactant coverage. The results obtained agree qualitatively with experimental results for Sb/Ag/Ag(111) on flat surfaces.