Can you use a merchant resource just as it is?
If you want to just use it for making renders, that’s fine. If you want to create something for sale, you have to change it significantly.
Would it look like any other texture for victoria 4 when you render it?
Yes, it’ll be somewhat plainer than most, and they don’t always come with the material presets, sometimes they are just the raw texture files.
What I am mainly looking at is something like this: http://www.renderosity.com/mod/bcs/gfr7-v4/73737
This product is face texture only. You would have to check with the vendors other sets to see if there is a close match to use on the rest of the body or use it with another body texture which could give you some odd results.
Before you buy a Merchant Resource, it is a good idea to read the readme. If vendors have special guidelines, they will be spelled out there.
Merchant resources can be used for personal use out of the box. If you wish to use them as a base for making your own textures, you will have to alter them using human resource photos. The generalized rule for altering to take an MR to your own original texture is at least 50% although some may require more.
Most creators of MR’s will not allow the MR to be used to make freebies.
All of this will be in the readme. If it isn’t or you’re not sure, email or site mail the vendor and ask. It’s always better to know than to guess. It’s been a couple of years since the last one but copyright infringement and all that goes with it is nothing new in the Poserverse.
If you are looking for human resource phots, 3dsk is the best source. You can also find packages at Rendo.