ID : 10511
Skill should land while hitting from the front.
http://l2wiki.com/Reverse_-_Othell_Rogue
The only skill that needs to be behind the target is Blood Stab ID: 10508 (it's working ok)
http://l2wiki.com/Blood_Stab_-_Othell_Rogue
Here you can see a video where the Othel rogue is using reverse from the front, for example in the min 3.12
http://www.youtube.com/watch?v=qEZlarMSg7U