The theoretical expression deduced by Mola and Heras from the Mayadas–Shatzkes model of monocrystalline thin film resistivity is approximated assuming that the Sommerfeld relation is valid and introducing corrections to the Matthiessen's rule.The approximate expression of kρf /ρ0 deviates from less than 6% in the 0.01–2 k-range, 0–0.5 p-range and 0.1–0.62 r-range.