[offbody]

Well, I do not know much, but this:
You can add two lines in TORRC file
ExitNodes 107.189.11.86
StrictNodes 1
for Tor to use exact IP
or
ExitNodes {US}
StrictNodes 1
for Tor to use only US exits
Simple, but does not work -- I just give you the path where to dig out.
Regards