RF-sheath induced heat loads are identified from infrared thermography measurements on Tore Supra ITER-like prototype and JET A2 antennae, and are quantified by fitting thermal calculations. Using a simple scaling law assessed experimentally, the estimated heat fluxes are then extrapolated to the ITER ICRF launcher delivering 20MW RF power for several plasma scenarios. Parallel heat fluxes up to 6.7MW/m2 are expected very locally on ITER antenna front face. The role of edge density on operation is stressed as a trade-off between easy RF coupling and reasonable heat loads. Sources of uncertainty on the results are identified.