  The renormalization group (RG) running of the neutrino mass operator is
required for comparing the predictions of neutrino models at high energy with
the experimental data at low energies. In the type I seesaw scenario with n_G
right-handed neutrinos, the RG running is also performed in the effective
theories above and between the thresholds given by the masses of the
right-handed neutrinos. At these thresholds, the effective theories are
matched. When calculating the two-loop RG running, the matching has to be
performed at the one-loop level. In this work, we calculate the one-loop
matching formulae in the MSSM extended by n_G right-handed neutrinos using
supergraph techniques. Moreover we present a general formula for one-loop
matching of superpotential operators which can readily be applied to any
supersymmetric theory where chiral superfields are integrated out.
