The AC resistance is an important factor in determining the insertion loss of miniature MMIC circuits over their passband. The metallisation of an MMIC is in the form of rectangular strips. The paper gives detailed formulation and analysis of the isolated rectangular strip conductor. Meixner's edge condition for the rectangular strip with loss is investigated. It is found that such a condition is obeyed. Based on this condition and the analysis, a simple and accurate curve fitted approximation of the AC resistance is presented.