This is something only for the die-hard ppc collector. This was the printer and publisher Bruno Buerger & Ottilie from the city of Leipzig, Saxony.
It needs plenty of time, requires an own bigger (or access to a) ppc collection to compare, a good eye for details and best some knowledge of (old) printing processes and their characteristics. Although “Ottilie” was normally a female surname then it stood here for the business partner “Carl Ottilie”B.
Some printers put their initials in regular type with or without card/job number on ppc’s.
Sometimes in very small type or hidden inside picture/ornaments etc.
More often any initials found imprinted stood for the postcard publisher but not the printer. Nister, others by Bruckmann, Munich) used also a special designed logo on cards, however.