Computing Porosity with Source Term for UDS

How to account for porosity while specifying source term for a UDS with mass flux as flux function?

When specifying a source term for a User-Defined Scalar (UDS) with mass flux as the flux function in Ansys Fluent, the treatment of porosity depends on the velocity formulation you are using.

(a) If you are using the superficial velocity formulation, the source term does not need to be multiplied by porosity when the flux function of UDS is mass-flux.
(b) However, for physical velocity formulation, the source term should be multiplied by porosity if the flux function is mass-flux