https://www.youtube.com/watch?v=1J1M_bcol68
Steps
1. Start on the field edge 30 metres from the corner.
2. Press Start Boundary then Offset.
3. Enter distance from the antenna to field edge.
4. When ready press Start.
5. Drive around the field edge...back to where you started.
6. When the starting point is reached... the map auto closes and is displayed.