A poser.exe file is a file that poser needs in order to treat that runtime like one of it's own and be able to search for it. No need to "copy" the poser.exe file though... Just make a new text file and change the name to "poser.exe", which tricks poser into thinking that the runtime you made is a real runtime.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi