If you are leveraging GeekSeller to create and maintain your product listings, Finale can push stock updates into GeekSeller via FTP.
Finale can be configured to periodically push an FTP stock report directly to Geekseller. Geekseller will then in turn update your marketplaces. Finale will not communicate directly with the marketplaces with this configuration. If you choose to have Finale also update your marketplaces directly, you may need to reach out to GeekSeller to request that the stock updating is disabled on their end.
First, you'll need to obtain your FTP credentials from GeekSeller. Once you do this, follow the steps in this help article.
After the configuration is set up in Finale, you'll then need to configure it in GeekSeller. Please follow the steps in this GeekSeller help article.