How to use GPS proximity sensor with Smart Alarm?

I deleted the Smart Home Monitor from my Smartthings Android app to make the Smart Alarm app my only alarm controlling system. I cannot find a proximity sensor disarm option in Smart Alarm. Is it there and I am missing it? If proximity sensor function is already in Smart Alarm, where do I find it? I plan to take a suspenders and belt approach. I set up a 4 button key fob to keep inside the entry door that I always use, to disarm the alarm. However, I would also like to use proximity sensor. That way, I would hope to count on the proximity sensor to turn off the alarm when I am on my property, but if proximity sensor fails, which I have read it frequently does, or if I come onto my property without my phone, I can still use the 4 button key fob to disarm the alarm siren. Please advise. Thanks, all.