The endothermic nuclear reaction between thermal tritons and high energy protons can represent an important contribution to the total neutron yield in tokamak plasmas heated by radio-frequency waves, as previous JET experiments have demonstrated [7]. A detailed study is reported in a paper [2] in this issue. In this accompanying Letter we report the first systematic measurement of the scaling of the proton-Triton (pT) nuclear reaction rate as a function of the total energy content and perpendicular temperature of the fast protons heated by radio-frequency waves. It is found that the pT neutron rate increases almost linearly with the fast proton temperature and the total energy content, and appears to saturate when the fast proton energy is larger than ~0.7MJ.