  Magnetic molecules adsorbed on a superconductor give rise to a local
competition of Cooper pair and Kondo singlet formation inducing subgap bound
states. For Manganese-phthalocyanine molecules on a Pb(111) substrate, scanning
tunneling spectroscopy resolves pairs of subgap bound states and two Kondo
screening channels. We show in a combined approach of scaling and numerical
renormalization group calculations that the intriguing relation between Kondo
screening and superconducting pairing is solely determined by the hybridization
strength with the substrate. We demonstrate that an effective one-channel
Anderson impurity model with a sizable particle-hole asymmetry captures
universal and non-universal observations in the system quantitatively. The
model parameters and disentanglement of the two screening channels are
elucidated by scaling arguments.
