To install,

Automatic,
Simply use Nexus Mod Manger

Manual,
Drag and drop Realistic Sneak Damage.rar's contents into the Skrim folder
(C:\Program Files (x86)\Steam\SteamApps\common\Skyrim) then activate the .esp
in your plugins list.

Load Order,
Only requires two master files: Skyrim.esm and Update.esm