  Relativistic reflection features are commonly observed in the X-ray spectra
of stellar-mass and supermassive black holes and originate from illumination of
the inner part of the accretion disk by a hot corona. All the available
relativistic reflection models assume that the disk is infinitesimally thin and
the inner edge is at the innermost stable circular orbit or at a larger radius.
However, we know that several sources, especially among supermassive black
holes, have quite high mass accretion rates. In such a case, the accretion disk
becomes geometrically thick and the inner edge of the disk is expected to be
inside the innermost stable circular orbit. In this work, we employ the Polish
donut model to describe geometrically thick disks and we study the iron line
shapes from similar systems. We also simulate full reflection spectra and we
analyze the simulated observations with a thin disk relativistic reflection
model to determine the impact of the disk structure on the estimation of the
model parameters, in particular in the case of tests of the Kerr hypothesis.
