GP appraisers are all capable of appraising undifferentiated general practice, but for extended roles your appraiser needs further assurance from your supervisor(s) about your performance in those roles.
Extended Practice is:
An activity that is beyond the scope of GP training and the MRCGP, and that a GP cannot carry out without further training or,
An activity undertaken within a contract or setting that distinguishes it from standard general practice or,
An activity offered for a fee outside the care to the registered practice population.