I still remember when the performance appraisal system was first introduced in our company. We had a clear-cut appraisal manual written by HR professionals, and external help was sought from consultants. Following that, everyone underwent classroom training on what performance appraisal is and how it should be conducted.
Recommendation for Performance Management
In your case, I recommend drafting a performance management policy and organizing a one or two-day workshop on performance management to create awareness and familiarize people with performance management tools. Unless people are trained when adopting a new policy, there is likely to be strong resistance from the majority.
Regards,
Raju Prasad