Firstly ur Question has no apparant meaning (Excuse me if I'm sounding a bit rude, but that's the case).

Secondly, the force of friction entirely depends on the force applied upto a certain limit, as soon as the force exceeds the value, it becomes mgcosx, where x is the angle of inclination.....below the limit it depends on ur direction of application of force, net resultant etc. Ur Qn should've been referred to some specific problem, it's quite difficult to say the answer just like this.........

listen man!!!!!!!!!!!!!your question has no useful meaning.you should first tell us whether the body is at rest or in motion,the angle of inclination of the wedge,which side of the wedge the body is on etc!!!!!!!!!!!!!!!

well firstly you must think that why friction acts! well friction acts to oppose the relative motion between 2 bodies in contact! on a rectangular wedge the blocks has the tendency to slip down and hence to oppose this motion the friction will act in upward direction parallel to the plane of the wedge! now you can apply the formula f=UN where U is the coefficient of kinetic friction and N is the normal reaction force! and remember if the friction is static then its value will only be equal to the component of the weight along the direction parallel to the plane of the wedge and if it is just about to move then it  will be equal to U'N where U' is the coefficient of static fricition!