Yep .. it looks there wasn't a rule for the font size and its shape. I have seen then as tall as the chevron and a slightly lower or small that were applied inside of the marking. Also their colours were different. Also instead of letters there could be digits if it was a Stab of a Gruppen.
the source: the net.
the source: Artwork profile Schlachtgeschwader 10 - SG10 Focke-Wulf Fw 190s
the source: the net.
the source: Artwork profile Schlachtgeschwader 10 - SG10 Focke-Wulf Fw 190s