Fernando, forgot to thank you for posting those pics of the regiment/rac marks. I am also of the opinion that the R or RX for that matter, stands for regiment once we ruled out (in the original thread) that it was for 'rack number' (ruled out by the fact that the German word for rack is 'Gestell' ), whereas 'regiment' is the same in German and thus starts with the leter 'R'.
I finally went back to "Arm& Armor in Colonial America 1526-1783" to check Peterson's footnotes. The one he lists for the jaeger sword is a mouth full-
"Oberleutnant Deiss, "Blank-und Schutzaffen Preussens von 18 Jahrhundred ab" Zeitschrift fur Historische Wafenkunde
, Band V (1909-11), 324-330. Notes compiled by Col Harry Larter from specimens in German musems and he paintings of Richard and Herbet Knoetel, Menzel, ad C. Rochling."
Does anyone recognize any of these sources?
Here's a contemporary pic of jagers, with typically nearly out of shot pics!
Note the straight sword blades and rectangular knucklebows
And another straight sword, coveed by cloak and not sure if contemporary-