An analytic theory proposed in Ref. 1 [V. S. Sukhomlinov and E. N. Fafurina, Zh. Tekh. Fiz 65(4), 9 (1995); Tech. Phys. 40, 295 (1995)] for the backscattering of light ions by a solid surface is developed for the cases of multicomponent materials and materials in which the concentrations of some of its components vary with depth.