An admin wants to create new custom metric on the Account product period forecast component...

Create a custom field on Account Forecast, create a custom of field on account product, map both of new fields in the account forecast setting page.

Create a custom of field on account product period forecast, , create a custom of field on account product forecast, map both of new fields in the account forecast setting page.

Create a custom of field on Sales agreement product, Create a custom of field on Sales agreement product period, map both of new fields in the Sales agreement setting page

Create a custom of field on account forecast adjustment, Create a custom of field on account forecast adjustment period, map both of new fields in the account forecast setting page.