How to add an error/warning message if FTE exceeds by 1 in Employment using Autocomplete Rules?

Summary:

I would like to add an error/warning message when the FTE will succeed by 1 while Hiring an Employee with the use of Autocomplete Rule via HCM Design Studio.

Content (required):

Adding error/warning message in Hiring an Employee

Version (include the version you are using, if applicable):

22B

Code Snippet (add any code snippets that support your topic, if applicable):