Currently the export of the GPS points into a KML file from RD Manager Online is not functional.
With the log data export from the RD8200 you can enter the GPS data and plot these points manually.
This is now a case of manipulating the data to suit you as a user, below is how to display the points as a heat map
Now the GPS points will be displayed in a heat map.
Ensure "Map Labels" are on for road/street names to be included on the map.