  The hotspot emission of accreting millisecond pulsars (AMPs) undergoes
scattering in the accretion flow between the disk inner radius and the neutron
star surface. The scattering optical depth of the flow depends on the photon
emission angle, which is a function of the pulse phase, and reaches its maximum
when the hotspot is closest to the observer. At sufficiently large optical
depths the observed pulse profile should develop a secondary minimum, the depth
of which depends on the accretion rate and the emission geometry. Such a dip
evolving with the accretion rate might explain the phase shift and pulse
profile evolution observed in AMPs during outbursts. Accounting for scattering
is important for accurate modeling of the AMP pulse profiles in order to
improve the accuracy of determination of the neutron star parameters, such as
their masses and radii. In this paper we present a simplified analytical model
for the Thomson optical depth of the accretion funnel, and apply it to
simulating the pulse profiles. We show that scattering in the accretion funnel
has a significant effect on the pulse profiles at accretion rates of $\dot{M}
\gtrsim 10^{-10}~{M}_\odot\, \mathrm{yr}^{-1}$. Our model predicts a gradual
evolution of the pulse profile with the accretion rate that appears to be
consistent with the observations.
