  We study the radiative heat transfer between two semi-infinite half-spaces,
bounded by conductive surfaces in contact with vacuum. This setup is
interpreted as a four-terminal mesoscopic transport problem. The slabs and
interfaces are viewed as bosonic reservoirs, coupled perfectly to a scattering
center consisting of the two interfaces and vacuum. Using Rytov's fluctuational
electrodynamics and assuming Kirchhoff's circuital law, we calculate the heat
flow in each bath. This allows for explicit evaluation of a conductance matrix,
from which one readily verifies B\"{u}ttiker symmetry. Thus, radiative heat
transfer in layered media with conductive interfaces becomes a
Landauer-B\"{u}ttiker transport problem.
