If you’re going to have a successful performance appraisal, you have to remember what the point of the whole adventure is:
To make the employee feel encouraged that they made the right choice to work for you.
They need to have positive feedback. Then choose an area that can be improved, but stick to one. If you have several, defensiveness kicks in and you won’t be heard anyway.
If you find it hard to narrow down your negative comments, you should ask yourself if this person is in the right seat, or on the right bus. And that is a different conversation.