guess its your call end of day. would think the SRP or CSP would hold definitive answer to your obligations but suspect basic first aid would suffice. just with rugby guess there is chance of significant head/neck injury and you should at least carry hard collar and knowledge to log roll, immobilise and await ambulance when required. dont think you will be intubating or epi-penning anyone but maybe should carry a bag and mask and pen just in case!