Here are the steps to restrict access to your Microsoft Forms form:

1. Under the Edit tab, select Make this form private.
2. A pop-up will appear; click Yes to confirm.
3. Under the Invite People tab, click New and enter the email addresses of those who are allowed to view the form.
4. Once invited people appear in the list, select Can view in the Permissions column.
5. At the bottom of the page, enter a message such as Thank you for completing the form.