  We examine the spectroscopic signatures of tunneling through a Kitaev quantum
spin liquid (QSL) barrier in a number of experimentally relevant geometries. We
combine contributions from elastic and inelastic tunneling processes and find
that spin-flip scattering at the itinerant spinon modes gives rise to a gaped
contribution to the tunneling conductance spectrum. We address the spectral
modifications that arise in a magnetic field necessary to drive the candidate
material $\alpha$-RuCl$_3$ into a QSL phase, and we propose a lateral 1D tunnel
junction as a viable setup in this regime. The characteristic spin gap is an
unambiguous signature of the fractionalized QSL excitations, distinguishing it
from magnons or phonons. The results of our analysis are generically applicable
to a wide variety of topological QSL systems.
