Right click to send file to USB in Finder

That's not on the contextual menu. Just drag it.

Dragging copies, while cmd-drag moves.

You could also create an Automator Service to move the file, but you'd have pick the destination from a list of choices. Much simpler to drag and drop.

Here is an applescript the would work. Just change "<USB drive name here>" to the name of your mounted USB drive.

tell application "Finder"

set destination_Folder to "<USB drive name here>:"

try

moveselectiontodestination_Folder

end try

end tell

You can add it as a selection in your right-click menu if you add the applescript to an automator service.

Ok. Drag and drop is easy too. Creating an automator service is pretty simple though, actually. I will give you a step-by-step in case you change your mind.

1. hit Command + Spacebar to bring up the spotlight menu. Then type "automator" and hit enter.

2. select File-->New. Then pick "Service"

3. In the search bar at the top-left, type "run applescript" and then drag the "Run Applescript" action into the pane on the right.

4. Now just make your automator window look like this:

http://i.imgur.com/cs0SuEP.png

5. Save it.

Thats it! Now your right click menu will allow you to move files to your USB drive.

It is possible to make it find the usb volume, regardless of what the name is, but the script would have to be changed. If you are interested in doing this, start a new thread in the Applescript section of these support communities.