convert .png created with maperative to .geotiff

Dear All,

I like to create an offline-map to use it with Qmapshack. By using "Maperative" with an OSM map. I created a .png file with comes with a .georef file:

<georef> <srs> <id>EPSG:3857</id> </srs> <origin> <x>865049.43693115131</x> <y>6659677.6895479513</y> </origin> <cell-width>4.1076778338027751</cell-width> <cell-height>-4.1076778338029394</cell-height> </georef>

How can I convert it to a geotiff or any other format to create a .vrt in Qmapshack, please ?

Thank you very much !

Kind regards

Rawbit