  We develop a method to study the effect of the superconducting transition on
resonant inelastic X-ray scattering (RIXS) signal in superconductors with an
order parameter with an arbitrary symmetry within a quasiparticle approach. As
an example, we compare the direct RIXS signal below and above the
superconducting transition for p-wave type order parameters. For a p-wave order
parameter with a nodal line, we show that, counterintuitively, the effect of
the gap is most noticeable for momentum transfers in the nodal direction. This
phenomenon may be naturally explained as a type of nesting effect.
