  We derive the two-channel (TC) description of the photoassociation (PA)
process in the presence of a magnetic Feshbach resonance and compare to full
coupled multi-channel calculations for the scattering of $^{6}$Li-$^{87}$Rb.
Previously derived results [P. Pellegrini et al., Phys. Rev. Lett. 101, 053201
(2008)] are corrected. The PA process is shown to be fully described by two
parameters: the maximal transition rate and the point of vanishing transition
rate. The TC approximation reproduces excellently the PA transition rates of
the full multi-channel calculation and reveals, e.g., that the enhancement of
the rate at a resonance is directly connected to the position of vanishing
rate. For the description of two independent resonances it was found that only
three parameters completely characterize the PA process.
