In English grammar, the concept of "person" refers to the use of different pronouns indicating from whose point of view something is written: first person (I, me, we and us), second person (you) and third person (he, she, they and them). Although it may seem odd to write your own performance appraisal using "he" or "she" (instead of "I"), using the third person makes it easy for your supervisor to incorporate her comments and then sign off on your review as if she had written it herself. The third person convention also makes your evaluation seem more objective and less personal.
Read your appraisal over carefully and highlight each personal pronoun. Remember that the personal pronouns are divided among the three "persons"--first person, second person and third person.
Replace each first person pronoun with the appropriate third person pronoun. For example, if you are male and you initially wrote, "I was responsible for initiating a new system to increase blintzer coil output," change it to "He was responsible for initiating a new system to increase blintzer coil output." If you are female, change "I used my mathematical skills to solve the overheating problem" to "She used her mathematical skills to solve the overheating problem."
Double-check that all the pronouns are in the third person after you've completed your performance evaluation draft. Set the draft aside for awhile, and then read it over again to make sure it's all correct.
After you've reread your draft, try reading it out loud to be sure you haven't missed or overlooked any mistakes.