  We present calculations of the conductivity tensor \sigma of a 2D-system with
the Rashba spin-orbit interaction (SOI) in an orthogonal magnetic field, with
allowance for electron elastic scattering by a Gaussian \delta-correlated
random potential in the self-consistent Born approximation. The calculations
are performed proceeding from the Kubo formula using a new exact epresentation
of the one-particle Green function of the 2D-system with SOI in an arbitrary
magnetic field. We have obtained the analytical expressions for the density of
states and \sigma which have a simple interpretation in terms of the
two-subband model and hold good in a wide range from the classical magnetic
fields (\omega_{c}\tau\ll 1) up to the quantizing ones
(\omega_{c}^{}\tau\gtrsim 1). The numerical analysis of the Shubnikov - de Haas
oscillations of the kinetic coeffitients and of their behavior in the classical
fields region is performed.
