The first right-hand rule determines the directions of magnetic force, conventional current and the magnetic field. Given any two of theses, the third can be found.
The second Right-Hand Rule determines the direction of the magnetic field around a current-carrying wire and vice-versa
So, assuming that a magnetic field exists and its direction is known and assuming that a charged particle moves in a specific direction through that field with velocity (v(, to determine the direction of force on the particle we should use the second right-hand rule.