Adding registration keys to initial-web-services

In the Docs for using ZCM in a VDI environment, it mentions that you can add a registration key to the initial-web-services file. (Here: https://www.novell.com/documentation.../b16rrxx9.html). I can't find any info on how to do that. Is it as simple as adding it as a line beneath the certificate?

Can someone point me in the right direction?

TIA,
Adam