Need to have a validation rule to restrict Line Manager to add only Country specific DOR

Summary:

My Team→ Document records: When Line Manager tries to add a Document of records, the document type LOV shows all active documents and able to add any document to any employee irrespective of country specific.
Business requirement- Line manager should be able to add only country specific document type

eg: If Line Manager has direct reports from different countries (USA,Canda,Mexico)

Now Line Manager should be able to add Document type (country = USA) to US employee only. System should restrict LM when tries to add any other country specific DOR.

In order to achieve this, we are trying to add a validation rule in VBS and unable to add conditions specific to this