How to use '%include' in kickstart configuration to load additional kickstart information from file on CDROM?

Issue

Objective is to use '%include' statements in the kickstart configuration file, to make the kickstart process modular for automatic cdrom installations on multiple systems. In the command section of the main kickstart configuration file, a line with '%include /custom_ks/ks1.cfg' is added. The intent is to load the contents of 'custom_ks/ks1.cfg' file from the CDROM.  However, this file cannot be found on the CDROM by kickstart during the installation process.