Welcome to the Rob Roy RMB series of Letterbox Hybrids. Rob Roy Reserve is a wonderful location to visit for Bushwalking and Geocaching, and is teaming with Wildlife to observe. The views from various peaks are amazing. You just have to slog up that hill first :-).
Take all the usual precautions for a walk up the mountains including plenty of water in the summer.
The stamp in the cache is to remain in the cache. Feel free to use it in your Letterbox Hybrid Stamp Logbook (if you have one) and also if you have a personal stamp please use it in the cache logbook.