We modified the invoice and called it Cert-actually we have several for different types of certifications that customers require.  Works quite well.

Karen.... you should have been here you could have picked up some extra work.... maybe you'd be willing to share your info so the rest of us can get started.

Furthermore a field for the US census Schedule B number  would be great... perhaps it could be entered through IN-B with all of the other part data

Pro Forma only is appropriate as a Commercial invoice is mainly for reference and data collection. The shipping company uses it for invoicing the shipment cost. We already have a SO to invoice from.  
 
The schedule B number is a (there are others) material reference that is internationally recognized and administered by the US government. It is necessary on international shipments (import/export) where a given part's total shipping value exceeds $2500. There are 12 characters in the code e.g. 7306.90.5000 no commodity description is necessary.

Info on NAFTA certificate of origin (CO) at
http://www.cbp.gov/nafta/docs/us/guidproc.html#6%20CERTIFICATE%20OF

Lenette,
If someone could tell me how, I could post a couple of screen shots, or setup a link to show you my certifications.  We print them on three part NCR paper so the QC Manager can sign them.  Since they work off the invoice, we can print them after the invoice is completed, or before if necessary.