I don't think the advice above is correct! You can only sign your name as a PE in the state in which you are registered. If youi are registered in Ohio and live/work in Idaho, you cannot sign or have in your signature block PE after your name if indeed you live/work in Idaho. To do so is to purport to be "practicing engineering" in a state in which you are NOT licensed. Be careful here, you can get bit and bit hard on this one.
You can, I believe sign your name, "Joe Blow, PE (licensed in Ohio)" and be OK. Here is where a good understanding of the state rules comes into play. I am licensed in more than one state and have carefully read the rules of each respective state. The state rules clearly specify that if you are not licensed in the state, you cannot use PE after your name if indeed you are not licensed in the state. Read the minutes of the last state board meetings if you have doubt. My review of several state board meetings is that many engineers get caught in this trap and end up being fined up to $5000 for advertising their services in a state in which they are not licensed. This matter is normally addressed in the disciplinary actions part of the board minutes. Again, if in doubt, call the state board and ask for clarification. However, I believe that I am 99.99999% correct on this interpretation of code.