What is the nature of your industry? Why would you like to have only a self-appraisal form? Are they mature enough to understand the seriousness of this form? Do you know the risks involved in self-appraisal? Do you have a policy on Performance Appraisal (PA) well in place? When employees join the company, during induction itself they should be told when their appraisal will take place.
The important point is that PA concentrates only on individual performance. We need to go beyond and measure business performance. For this, you need to have a well-designed policy on Performance Management System (PMS). There was a query in this forum on PMS. I have replied to this post. Click the following link to refer to the reply:
https://www.citehr.com/511936-pms-company.html
Though the heading is for IT companies, the reply is applicable to all types of industries. In the above link, you will find several other links. Go through all the links patiently. It will improve your awareness of the subject.
For further doubts, you may call me on my mobile number.
Thanks,
Dinesh Divekar