Circuit Tools software can be used to create a reference lap for use within VBOX lap timing systems. To create a lap timing reference lap file (.ref), load a previously recorded .vbo file which includes the desired lap in to the software. Ensure the lap you would like to use is the Datum within the Session Window and then press the Export datum lap as reference lap file button on the Session Menu to save the .ref file locally to your computer.
You can find instructions on how to load the file into VBOX lap timing systems in the respective product's user guide: