Hi Sanjay,
You can definitely have a parent database which is RAC, either dsource or VDB and then create another VDB that is a single instance. This is accomplished by specifying the environment, standalone, and or only selecting one node of a cluster environment.
You can also go from a single instance parent database, dsource or VDB and provision a RAC VDB by specifying a cluster environment and selecting multiple nodes to provision to.
Our documentation discusses VDB provisions here:
http://docs.delphix.com/display/DOCS40/Provisioning+VDBs+from+Oracle+and+Oracle+RAC+dSources