That button is very awkward to get to.
One really has to get one's head down in the footwell and look up to the under-dash panel. The button is quite recessed as one normally doesn't have to use it. Once the TPMS system is set at the desired inflation pressure it doesn't require resetting unless one wishes to run the tyres at a different pressure, for example if one had a full load of passengers and luggage, or one was to run for extended periods at high speeds.
The RC300h only has the one recommended pressure for all situations.