Both Judy Gale Roberts at Intarsia.com and Ray at Seyco sell foot control switches.
https://intarsia.com/collections/hardware/products/foot-switch and http://seyco.com/fs-3-universal-15-amp-foot-switch/
However, I had previously purchased one from Amazon before I got started and found either Judy's or Seyco's site. The second used saw I bought came with the saw.
Mine is the saw is "on" and running while stepping on it and stops immediately if I lift my foot. I much prefer using the foot pedal while sawing and use it both when I sit or stand at the saw. As noted, you control the speed with the variable speed knob on the saw its self.