Depending on how long you've had this and your overall body type, it would be a good idea to talk to your doctor before doing anything cosmetic.   Sometimes that fatty "hump" can be a sign of Cushing's disease which is a disorder of the adrenal gland wherein the gland secretes too much cortisol. 

After you're sure this isn't a medical problem, I hate to say this but radiofrequency just doesn't work for the neck area.  Things to consider are liposuction or you might want to see if anyone in your area has a Zeltiq.  This is an interesting newer (so not a lot of data) fat reduction technology that uses cold (cryotheraphy)  to reduce fat cells.   Avoid the Zerona who's name sounds similiar but is different - results can be initially good but the fat just recurs.    Hope this helps.  Dr. I