A molecular model is proposed to study the enantioselective adsorption of chiral species on metallic surfaces modified through the preadsorption of another chiral species, known as template surfaces. It is found that anisotropic and exclusive interactions among adsorbed species are essential factors in the enantioselective process. It is shown how the formation of compact structures explains the fact that an enantiomer of species B having the same symmetry as the template species A can be preferentially adsorbed with respect to the other enantiomer of species B, thus producing enantioselectivity. The model predicts enatioselectivity peaks on a limited range of the template coverage, as typically observed experimentally in some systems.