We report the implementation of isolated resonance RRKM theory for the titled reaction with resonance characterizations derived from exact quantum dynamics calculations. Only nonrotating HCO is considered, i.e., total angular momentum of zero. The sensitivity of the resonance widths on the pressure dependence in the approach to the low pressure limit is examined. This discussion includes the effect of tunneling i.e., very narrow resonances, on the value of the low-pressure limit.