We study the magneto-resistance of a two-dimensional electron gas (2DEG) in a one-dimensional lateral superlattice potential. The superlattice potential is generated with so-called interdigital field-effect electrodes. Interdigital gates enable us to precisely control the mean electron density and the strength of the superlattice potential within a broad range by means of two voltages. Calculated values for the strength of the modulation beneath interdigital gates are compared to those obtained from commensurability oscillations. We discuss the importance of oscillation damping by elastic scattering processes and the influence of the potential modulation strength on the positive magneto-resistance.