For the Numbstone - I would say that yes, it requires a RR. However, the range for it would be "touch" since the spell is on the stone. Thus, the caster has to hit the target, do a crit, and then the target has to fail a RR (but it is harder than if the spell were cast at a distance).
For the other spell, that changes the crit of the attack, so no RR is required (i.e. it affect the attack, not the target). That should be your guiding principle -- affects attack - no RR; affects target of atack - RR.