A supplemental feed is a secondary data source used to provide more details or update existing details, such as required or optional product attributes, that may be missing from your primary feed. A supplemental feed can't be used to add or remove products or be used as a standalone feed.

In your Merchant Center account, click the Products drop down menu from the left navigation panel. Click Feeds. Locate your feed from the list of registered files. In the "Feed name" column, click the feed name associated with the file you'd like to submit.

The primary feed is a list of all of the products that you sell with attributes that describe those products. Some attributes are required for all items in your feed, some are required for certain types of products, and other attributes are recommended or optional.