I don't think Atrixx has an AMR. The essence of it is giving up Force Crush to pick up Deadly Saber without sacrificing Cascading Power (as the other marauder hybrids generally do). Deadly Saber, Rupture, Obliterate, Smash, Force Scream, Ravage and Vicious Throw all on cooldown. It's fine to delay Rupture by a GCD or two if you can get it directly
prior to a Smash. Try to keep Ravage within a Cascading Power buff (should be every third Smash exactly).
One perk of this spec is Deadly Saber's application is delayed by the use of Smash and Scream (neither of which exist in the Annihilation rotation), which means that you will generally get more ticks per activation than an Annihilation marauder will.