Hi,
I don't think you can do this as set out. The table would need to be wrapped in a second subform, set to flowed western. Your script in the add product button has references to objects (eg r1, r2 and _col3SF) that are not in your form, so the script is falling over.
Not sure of this is the best route. Maybe repeating individual subforms might be earier. For example each column would be in an individual subform set to flowed top to bottom. The add attribute button would add a row to the table in EACH subform. Then all of the table subforms would be wrapped in a western flowed subform and the add product button would add an additional subform.
Hope that helps,
Niall