Cermet composite thin film resistors of Cu and MgF2 were prepared by conventional vacuum evaporation technique at a pressure of 5 x 10(-5) torr and at 302 +/- 2 K. The composition by volume was varied from 10 vol% Cu and 90 vol% MgF2 to 100% Cu for thicknesses in the range 110 to 300 nm. Starting materials were co-evaporated from separate molybdenum boats. An empirical formula has been proposed to describe the resistivity-thickness relation for the thin film resistors. The resistivity-thickness relation was found to be of Arrhenius type with ln rho(f) being a linear function of inverse of film thickness in the entire thickness range investigated. A parameter S has been defined to be an estimate of the average separation of the metal islands in the composite thin films. It was observed that S increased with decrease in Cu content of the composite resistors. Another empirical formula has been proposed to describe the resistivity-composition relation for the same film resistors. The relation, obtained by regression analysis of the resistivity-composition data, was found to be exponential in terms of vol% Cu content of the Cu-MgF2 cermets.