The application limit of the MULTX program for predicting Renninger-scanning X-ray multiple diffraction data is extended in order to simulate Renninger scans for semiconductor single-crystal and heteroepitaxial structures recorded using synchrotron radiation. The experimental synchrotron-radiation Renninger scan for InP(006) bulk material is taken as the standard to analyse the effects of both the polarization factor and diffracted-beam path length. The polarization of the synchrotron-radiation beam is considered using a matrix approach. The diffracted-beam path length involved in the surface secondary beam cases is analysed taking into account the dynamical theory for perfect crystals and the kinematical theory as the limit of the dynamica...