Well, there is nothing fictitious or virtual about the force caused by a centrifuge. And, I don't hear too much discussion about its noninertial frame of reference, either. So, perhaps the physicists should explain themselves better.
Ratch
Ratch, I would say, perhaps you should learn physics better, but I'm contributing here to help PG answer his question, not to teach you physics. So, I understand that you don't get it, but I think physicists do explain themselves very well generally. So, go look at what they say, and I'm sure you'll get it.
PG, and Ratch,
As far as the question. Just to clarify, I should describe what a reaction centrifugal force is. First, the term centrifugal means a force directed out from the center, as opposed to centripetal which means in towards the center. The pseudo-force typically called centrifugal force is an outward force that exists in the moving non-inertial reference frame. This differs from the reaction centrifugal force, which is a real Newtonian force that is the reaction to centripetal force. Examples include the internal stress on a rotating turbine, motor or string, that keeps things from flying apart. In the case of a satellite orbiting a planet, the reaction centrifugal force is the force that the satellite places on the planet. Such forces are outward forces and hence are suitable to be called centrifugal. Again, physicists frown on this terminology, particularly for pedagogical reasons. They will insist all centrifugal force is virtual, fictitious or pseudo, and would prefer that you just say "reaction to centripetal force" to describe "reaction centrifugal force".
In my view, this is what makes the situation confusing. The physics is easy, but the terminology and established pedagogy make it confusing.