First, let me explain how the application works. When you set the anchor location in the app, it will remember the position, and based on the configured radius, it will alert you when the phone moves out of that radius. (To put it another way: the phone monitors horizontal movements based on GPS data it receives).
Regarding the anchoring itself, I can only suggest following the standard praxis of having a rode of at least a couple of times the depth distance. Of course, weather conditions & location specifics have to be taken into account.
After you have anchored the boat, you have to decide which distance to set in the application. In the suggested case where the rode length is a multiple of the depth, a good estimation is to simply set the radius as
(rode length + distance of the phone to the bow).
In the case of using the Anchor Pro application(Android) or Anchor Premium subscription(iOS), there is additional re-validation that you can do after you've been anchored for some time: Simply open the map view in the application and visualize the movement of the boat while anchored. This will show you how the boat was moving around the anchor location and will visually show if it would make sense to adjust the distance setting to make the application more / less sensitive.
This is of course general guidance and has to be reasonably adapted due to actual circumstances.
So for example, if you lay 100ft of a rode and the depth is 30ft, you can expect that the boat can drift a maximum of 95ft horizontally from the anchor(+distance of the phone from where the anchor is attached to the boat).
That is the number that you then set as radius since radius means the maximum allowed distance from the anchor to the phone’s location. This was the explanation for the “normal distance” setting.
Regarding the advanced distance, all the explanation for the normal distance is valid, on top of it you can also define an exclusion zone that has a different allowed radius. The idea is that instead of setting just a circle around the anchor’s location which specifies the allowed area, you set two different arcs that then form a complete circle. Small distance and big distance define the radius of each of the two arcs(radius from the anchor). The start/end angle then defines at which angle the big distance starts and stops. After you enter all four values, there should be a graphic representation of the set area below the settings.