Which products should I calculate a PCF for?

You should calculate PCFs for the products your customer is buying from you.

Once you create a PCF, you have the option to share the information with the customer who is engaging you as part of Procurewise. They will be able to match it to their purchases with you, and use the specific emission factor to calculate their own emissions. 

Therefore, you should calculate PCFs for the products your customer is buying from you. 

Note: you are still welcome to calculate PCFs for all your other products.