You want to know how to enable the feed in a Custom BO which is available in a standard BO, created via SDK.
SAP Cloud Application Studio
SAP Cloud for Customer
SAP Business ByDesign
Feeds in Custom BO's are not supported.
Feeds are only available for the standard BO's. This is a known scenario and has been added to the backlog. The functionality will be made available in one of the future releases.
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