  Over the last decade significant amounts of high-spectral and time-resolution
spectroscopic data have been acquired for a number of rapidly oscillating Ap
stars. Progress in the understanding of the information held by these data
requires the development of theoretical models that can be directly compared
with them. In this work we present a theoretical model for the radial
velocities of roAp stars that takes full account of the coupling between the
pulsations and the magnetic field. We explore the impact on the radial
velocities of changing the position of the observer, the mode frequency and
angular degree, as well as of changing the region of the disk where the
elements are concentrated. We find that for integrations over the full disc, in
the outermost layers the radial velocity is generally dominated by the acoustic
waves, showing a rapid increase in amplitude. The most significant
depth-variations in the radial velocity phase are seen for observers directed
towards the equator and for even degree modes with frequencies close to, or
above the acoustic cutoff. Comparison between the radial velocities obtained
for spots of elements located around the magnetic poles and around the magnetic
equator, shows that these present distinct amplitude-phase relations,
resembling some of the differences seen in the observations. Finally, we
discuss the conditions under which one may expect to find false nodes in the
pulsation radial velocity of roAp stars.
