How to expand RAID 5 array for R720 with extra disks 

Version 6.8.1 P10

appliance R720

Does anyone know how to add additional hard drive in to a Dell PowerEdge R720? 

I found below steps in Dell Community site, however I am wondering if anyone has done this before.

1. Add the physical disks to empty slots on the server. (does RSA appliance R720 have empty slots?)
2. Access the iDRAC interface (or maybe the Ctrl+R utility when booting) and add the extra  disks into the array.
3. "Reconfigure" the array. After this step, At this point the drive will now have the extra space.
4. In the OS, expand the partition to use the extra unallocated/free space. 

Has anyone done this before with our appliance with OS Redhat 5u11?  The only way this can be done is via OpenManage Server Administrator but  I can't find the driver for redhat 5x.  I can only see if for redhat 6..

http://www.dell.com/support/home/us/en/04/Drivers/DriversDetails?driverId=T9GYK&fileId=3365593027&os...

Thanks for your feedback in advance.

Nasreen