  We propose a new formula to explain circular velocity profiles of spiral
galaxies obtained from the Starobinsky model in Palatini formalism. It is based
on the assumption that the gravity can be described by two conformally related
metrics: one of them is responsible for the measurement of distances, while the
other so-called dark metric, is responsible for a geodesic equation and
therefore can be used for the description of the velocity profile. The formula
is tested against a subset of galaxies taken from the HI Nearby Galaxy Survey
(THINGS).
