Custom Entity Notes Roll-up/Activity Feed

I have a custom entity in CRM that is related to Account (many custom products to one account). Under the Account entity I can view notes via the activity feed or social pane. I have read other posts describing how to set your custom entity properties with Notes (includes attachments) and Activities boxes checked, however, there appears to be no option to attach the activity feed grid onto the custom entity's main form, nor does the custom entity appear in the Activity Feeds Configuration --> Post Configurations list. How do I get these notes on the Account activity feed???