Why not? If there is only one body where I probe the reaction force  its components should be  equal and opposite to the components of the applied load. I don't understand what is wrong..I'm interested in the force distribution on that body, since I don't know how the applied load distributes I was wondering if by analysing the components of the reaction force on that body I could find out the magnitude on each direction, but that would be a force which opposes to the applied load, not the load distribution itself...and in order to find out this load distribution it would be necessary to change the sign of the reaction force. Hope to be clear.

Applied load is a force which is applied on a body and distributes in a certain manner. Reaction force is how the body reacts to the applied load and its components can be different from the ones of the applied load if there are multiple bodies since the load in the latter case is distributed on a wider area. 

Is this wrong?

Thanks for the help