If you create a quotation, an order or an invoice you have to use the product or service listings. To be able to use this feature efficiently you need to consider that the description field of a product or service becomes a part of your PDF output of quotes, orders and invoices.
As illustrated in the following figure you may edit the desciption field after selectig a product or service and you may add a note. You may use the PDF Configurator to decide whether the description or the note or both will be included in the PDF output.