What is the correct way to set the R-switch on the RTH5160?

If you have only 1 R-wire (R, Rh, or Rc), set the R-switch to the up position and insert your wire into the R-terminal. If you have 2 R-wires (both R or Rh and Rc), set the R-switch to the down position, insert your Rc wire into the Rc-terminal, and insert your R or Rh wire into the R-terminal.