In the last few years, solutions for radiofrequency penetration in various homogeneous geometric shapes have been presented. As imaging is pushed to very high fields, including those available in small-bore units, some further understanding of the effects of relative permittivity, ϵr, and conductivity, σ, is required. To this end, we compare the RF field and power deposition out to fourth order in frequency, ω, for planar, cylindrical, and spherical shapes. The expected reduced power deposition as conductivity increases is easily described. Further, modifications to the equations for the spherical model resulting from several errors in the literature are given. Even for high fields, the expressions also reveal that for physiologic values of a and ϵ, the higher-order term in ω4 can become small, leaving the usual first-order functional dependence on w, a, e, and geometry and, hence, a near-uniform RF penetration.