I apologize. I just went back and read through the article completely --  
something I haven't done for some time. You're correct in your reading, but
there's a simple adjustment.

In the numbered list of instructions under the heading "Create a pop-up list
of products", eliminate steps 12 and 13. Also eliminate the entire part
under the heading "Insert a product list in your document". Instead, when
you have completed step 11, you'll already have an AutoTextList field in the
document (the field you inserted in steps 9 through 11). Using cut (or copy)
and paste, you can position that field anywhere in the document, and you can
have more than one of them if needed. Save the document at that stage, and
distribute it to users.

For your signature application, instead of making the default text something
like "product" or "signature", I'd make it something like "Right-click here
to insert signature". Otherwise, it's difficult to distinguish the
AutoTextList default text from any other text until it's already clicked.