Custom example Ardupilot

Anyone could help a bit in telling me what needs to be changed in custom-example in order to load Ardupilot firmware plugin instead of px4?

At the moment all I was able to do is include APM in pri file. All y other attempts destroyed pretty much everything.

thanks

I commented the following three lines in .pri

#MAVLINK_CONF = common
#CONFIG += QGC_DISABLE_APM_MAVLINK
#CONFIG += QGC_DISABLE_APM_PLUGIN QGC_DISABLE_APM_PLUGIN_FACTORY

Now it compiles and shows APM too