Hmm...
I am doing this with a KS for C7 and my /etc/rc.d/rc.local script get executed just fine on boot up without doing anything other than putting it in /etc/rc.d/
# ls -al /etc/rc.d/ total 72 drwxr-xr-x 10 root root 4096 May 18 07:37 . drwxr-xr-x 121 root root 12288 Jun 8 08:19 .. drwxr-xr-x 2 root root 4096 May 18 15:06 init.d drwxr-xr-x 2 root root 4096 May 18 14:56 rc0.d drwxr-xr-x 2 root root 4096 May 18 14:56 rc1.d drwxr-xr-x 2 root root 4096 May 24 10:21 rc2.d drwxr-xr-x 2 root root 4096 May 24 10:21 rc3.d drwxr-xr-x 2 root root 4096 May 24 10:21 rc4.d drwxr-xr-x 2 root root 4096 May 24 10:21 rc5.d drwxr-xr-x 2 root root 4096 May 18 14:56 rc6.d -rwxr-xr-x 1 root wheel 20080 May 18 09:14 rc.local
A little investigation shows that the problem was with the script that is supposed to execute, I used a simple script and it worked, actually the problem was #!/bin/bash was on the second line and not the first, bit embarrassing but glad that it is working.
Thanks, guys.