Mantle in BF4 not showing osd

I believe there is an inbuilt fps counter in BF4. You just need to enable it.
Press the tile key (~) and type in the console "perfoverlay.drawfps 1"

You can put it in the config file :
http://diaryofdennis.com/2013/11/04/how-to-load-bf-4-console-commands-on-startup-with-a-config-file/