So i found a 4" and 5" RSK by skyjacker. You're saying i should get one of them on top of 6" leafs? Wouldn't this leave the front 4/5" taller in the front?
Skyjacker does not make an RSK kit, certainly not for a OBS truck, so not sure what you are referring to here. Sky manufacturing makes a RSK kit typically used in conjunction with superduty springs for up to 5 inch lift. Anything beyond that, and you will have to buy lift springs (likely for a SD) to use in combination with an RSK kit, as others have mentioned. Either that, or just buy/have custom leaf packs made to accomplish 10 inches lift with your current setup, but it will ride terrible (with that much lift, its gonna ride terrible regardless if you go with RSK or not).
You will need a drop track bar bracket, longer brake lines, some form of modified steering setup (drop pitman arm and crossover steering etc etc...), carrier bearing drop bracket, likely some shimming of the pinion angle at the rear axle, possibly a longer driveshaft for rear although not sure on that, and almost certainly a longer driveshaft for the front if you want to retain 4wd capabilities.
Sounds to me like you may need to do a bit more research before going after this. 6 inches of lift you can get away with some stuff; 10 inches lift and things start to get a bit more difficult. There are Tons of RSK threads kicking around here and on various other forms that you can look at to see what it takes just to do 3-4 inches properly with the RSK mod.