How to issue a FREE TEXT INVOICE?
Go to menue accounts receivable - free text invoices - all free text invoices

go to new - free text invoice to open a new invoice window

1. Fill in all required information: customer account, invoice details, add a line with all the information - if required, the line can be removed and a new one can be added
2. open up the line details

change to tab "financial dimensions line" and fill in commodity, location and product

once all required information are filled in, post the invoice

You will receive an infolog stating that your free text invoice has been posted

If you would like to have more information, please check out the following links:
Invoicing & contracts fundamentals
Invoicing & contracts advanced