Basically you have to work on the No.of patients he is attending on daily basis. Retention of patients & new additions on monthly basis, monthly business ( in to that particular doctor's account - this includes the consultation / the cost of the tests, surgeries & medicines he prescribed - if you have an attached pharmacy ) & finally the feed back from the customers.
No of awareness sessions organized, the business acquired due to the sessions, Knowledge sharing to their team members, retention of their team members & their development.
I have given you some inputs, you can work out the KRAs / Measurement creteria / weightage. The above all activities can be distributed in to Financials ( business acquired), Business development ( awareness programs), Organizational Devpt ( Training & development of employees), Compliance is one more area you have to think - Compliance of all statutory & regulatory norms.
I believe that the inputs may be useful for completing the appraisal format.
Regards - kamesh