The Wiki also mentions how to resolve RFC error
CPIC Return Code 679 / ERROR: Transaction program not registered
to register the RFC program with rfcexec
Before this is run please check in AL11 whether /usr/sap/T3A/SYS/exe/run/rfcsdk/bin/rfcexec exists
OSS note 353597 also provides details on how to register a server program:
Cheers,
Remi