Generally in the larger civillian operators the C of A tests are done by training captains and the PMTFs will be done by line pilots for simpler tasks and training captains for more complex ones. In my company we designate individuals as qualified to do so. They undergo ground briefings on the various pitfalls awaiting them, the optimum methods to plan the flight and the pupose of the various test items. Normally we then carry out observed C of A flights to assess their competence to do them as P1.