The affected area must be thoroughly wetted with OdorXit solution and left to work for several hours. Because urine has a tendency to soak deeply into porous materials, wetting both sides of the hide will improve the penetration and reduce the amount of OdorXit required to do the job.
One additional note regarding urine contamination of a hide. Urine odor is produced when the urine residue is damp or wet. Since OdorXit solution is mostly water, the urine smell will get worse for a short time when first applied. This is absolutely normal and should be expected. By the same token, just wetting the contaminated area will produce the odor.
After you have completed your treatment of the urine contaminated hide with OdorXit and the odor appears to be completely eliminated, it is a good idea to spray a little water on the contaminated area to test for more odors. It's better that you find and fix the problem than to have the owner find it later.
Finally, you may want to offer your customer a quart of OdorXit solution mixed 1:30 to treat the flooring where the hide was laying when it was contaminated. Urine residue in the flooring does not go away be itself and if the pet missed or overflowed onto the floor, the floor needs to be treated as well. They can either spray or pour it on the floor and spread it around the area.