32.8.3. Registering a System in RHN Classic
rhnreg_kscommand is a utility for registering a system with the Red Hat Network. It is designed to be used in a non-interactive environment (a Kickstart style install, for example). All the information can be specified on the command line or standard input (stdin). This command should be used when you have created an activation key and you want to register a system using a key.
rhnreg_ksto automatically register your system, see the Knowledgebase article at https://access.redhat.com/solutions/876433.