Formula Field To Capture Date from a Report made from another table

The help that we need here is to show, (IF user=Supervisor then show number of agents for that user) so if the user is a supervisor the Headcount field should auto-populate the number of Headcount on his team.

Example:

On the image below, we have 3 supervisors on the list, so if supervisor 1 is to use the headcount validation form, he should be seeing 5 into the headcount field.