  The direction of polarization produced by a moving source rotates with the
respect to the rest frame. We show that this effect, induced by pulsar
rotation, leads to an important correction to polarization swings within the
framework of rotating vector model (RVM); this effect has been missed by
previous works. We construct relativistic RVM taking into account finite
heights of the emission region that lead to aberration, time-of-travel effects
and relativistic rotation of polarization. Polarizations swings at different
frequencies can be used, within the assumption of the radius-to-frequency
mapping, to infer emission radii and geometry of pulsars.
