Using ab initio information, the reaction path for the CH4+F-->CH3+FH reaction was traced and the coupling between the reaction coordinate and normal modes was analyzed along it. The FH product may be vibrationally excited due to the nonadiabatic flow of energy between the reaction coordinate and this bound mode, manifest in the large peak in the coupling term after the saddle point. It was concluded that the variational effects were due only to entropic effects. The rate constants were calculated for the temperature range 100-500 K using the variational transition state theory with different levels of calculation to calibrate the reaction path. Agreement was found with the experimental values when using the QCI/b3 shifted curve, avoiding the errors associated with the use of the single-point calculation.