We report variational Monte Carlo calculations which give amplitudes and phases of the reflected and transmitted components of states representing scattering of helium atoms normally incident on a superfluid 4He slab. The wave function describes a previously postulated condensate mediated process [J. W. Halley et al., Phys. Rev. Lett. 71, 2429 (1993)] and the results are consistent with uncertainty principle arguments suggesting that the transmission time for thin (but macroscopic) samples will be independent of slab thickness.