  Super Feynman rules for any superspin are given for massive $ \mathcal{N}=1 $
supersymmetric theories, including momentum superspace on-shell legs. This is
done by extending, from space to superspace, Weinberg's perturbative approach
to quantum field theory. Superfields work just as a device that allow one to
write super Poincare-covariant superamplitudes for interacting theories,
relying neither in path integral nor canonical formulations. Explicit
transformation laws for particle states under finite supersymmetric
transformations are offered. $ \mathit{C}, \mathit{P}, \mathit{T}, $ and $
\mathcal{R} $ transformations are also worked out. A key feature of this
formalism is that it does not require the introduction of auxiliary fields, and
when introduced, their purpose is just to render supersymmetric invariant the
time-ordered products in the Dyson series. The formalism is tested for the
cubic scalar superpotential. It is found that when a superparticle is its own
antisuperparticle the lowest-order correction of time-ordered products,
together with its covariant part, corresponds to the Wess-Zumino model
potential.
