@chrisdesign - You have a call on the white courtesy telephone, LOL.
Hi Dirk - Chris has been a professional retoucher for decades and probably is the best person on this forum to answer your question.
When I need to add some skin texture, I have a folder with quite a few high rez images of people's faces with nice texture, and I steal skin textures from them, LOL. I'll select a corresponding area of the face, make a copy, desaturate it, run it through the high pass filter, and then put that on a layer above the face I am retouching, and set the layer blend mode to either overlay or soft light. That way, it preserves the underlying color and lighting, but adds the texture from my face library. I've heard that there are some nice brushes out there, but since I do this sort of thing so infrequently, I've never looked into them.
Hang on for a few hours - I'm sure Chris will see this thread and respond.
Cheers,
Tom M
PS - BTW, I just noticed that when I first posted the above method, I forgot to include one important step. Around a small darker area like a pore, the high pass filter will generate areas both above and below the usual rgb=128 average value. If you apply that result directly to the other image using a straightforward "overlay" or "soft light" blending mode, this will produce unwanted lighter halos around the desired, darker pore areas. So, to look realistic, it's important to use the "darken" blending mode when blending the previous result with the original. When I get a chance I'll do a little demo and write it up.