Count records when two fields in single table are compared

I am working on a supplier scorecard.  I would like create an on time delivery as follows:

Table is Purch. Rcpt. Line

Count table records if the promised receipt date <= posting date

Posting date will need to be filtered (06/01/2021..06/30/2021)

Vendor No. will need to be filtered

I am familiar with the @NL Count Function.

Not familiar with filtering tables by comparing fields in the same table.  

Thank you for the help!

Sheila