Transport studies of molecular wire circuits require a description of the molecule and the leads. Here we focus on the molecule-lead interaction. We extend a time-independent scattering formalism to include a more realistic description of the interface. This allows us to obtain the conductance as a function of dimensionality of contact and of electrode, number of contacts, and geometry between molecule and interface. We study conductance in adlayers of molecules by considering transport through two identical wires. Implications for experiments are discussed.