RHEED intensities for flat and rough surfaces of Ge are computed for off-symmetry azimuths within the framework of dynamical diffraction theory. Two substantially different models of the scattering potential are used. Calculations employing the realistic model are compared with calculations for the simple potential model. The realistic potential is defined with the help of sum of Gaussian functions determined for each atomic layer. On the other hand, in the simple model only two, volume-averaged constants are taken into account to describe the potential (one value is set for the bulk, the other for the growing layer). It is discussed that simplified approaches may be indeed helpful for describing basic features of RHEED oscillations. However, obtaining precise information on growing samples requires the use of realistic approaches. (C) 2013 Elsevier B.V. All rights reserved.