Unique MetaTag Title Page to php page

I don't really understand this question? Are those *.php files part of drupal?

This module allows you to specify the meta tag values that appear in the part of your html output from Drupal based on a specific url path.

So an example is if you want to add the keywords "a b c" to the "www.example.com/contact" page that is generated by the contact module

Once you install this module, just go to the "Meta Tags" >> "By Path" admin menu and create a new rule for "contact" and add those keyword.

The actual meta tags you can edit for each path/rule is defined by the "Meta Tags" (nodewords) module.