Does Oracle Forms & Reports 12c require creating a configured repository via the RCU in order for the domain to be correctly created on the 12c Fusion Middleware installation? Our preference would be omitting the DB repository, but this does not appear to be a viable option. What is required in order to to implement the appropriate deployment (i.e. system components, managed servers, standard installation folder structure) using the "manual configuration" option?
you need a configured Metadata Repository by using the RCU in order to configure a domain for Forms & Reports, without a Metadata Repository you will have no chance to configure a domain for Oracle Forms & Reports 12c.