If you are having issues installing r1soft-cki, and getting an error message like this:
Unable to find a valid source directory. Please install the kernel headers for your operating system
Do:
yum install kernel-devel
If you are running one of the beta kernels, add --enablerepo=cloudlinux-updates-testing to the end of the yum command, like:
yum install kernel-devel --enablerepo=cloudlinux-updates-testing
Re-run r1soft-cki tool after that.