this has been a great addition to my site, however my products do not have branding, manufacturers, or UPC has I sell herbs. Google requires that i include an identifier as described below:

Please know that Unique product identifiers are product codes or other identifying values associated with an individual product. For all of your items, we recommend submitting all three attributes (‘brand’, ‘mpn’, and ‘gtin’) where available. In categories where unique product identifiers are required, merchants must submit the ‘identifier exists’ attribute with a value of FALSE when the item does not have unique product identifiers appropriate to its category, such as GTIN, MPN, and brand.
When to include: Required according to the Unique Product Identifier Rules for all target countries except for Canada and India. This attribute is recommended for Canada and India.

Type Boolean: TRUE or FALSE
Text/Tab delimited FALSE
XML <g:identifier_exists>FALSE</g:identifier_exists>
Is there any easy way to add this either via the config or in a text editor for each product?