  The critical current $I_c$ of single crystals of the iron pnictide
superconductor BaFe$_2$(As$_{1-x}$P$_x$)$_2$, has been studied through
measurements of magnetic hysteresis cycles. We show that the introduction of
surface irregularities in the $\mu$m scale significantly increase $I_c$,
primarily near the irreversibility magnetic field $H_{irr}$, where the surface
currents are the main contribution to $I_c$. Such an increase is consistent
with a theoretical estimate for the maximum non-dissipative current that a
rough surface can sustain, based on Mathieu-Simon continuum theory for the
vortex state.
