While looking up family history I found an old German marriage document which specified a dowry of "1000 Franks." With that, the families in question were from the Suggental/Waldkirch area in what is today the German State of Baden-Württemberg in the northern parts of the "Black Forest." The two possibilities I can think of is that either they used Swiss or French Franks or Francs because they may have moved from either area, or there might have potentially been some sort of Swiss or French influence in the area. The latter, to me, does not seem as possible.
Note that for the time period of interest there was no single German state, as we are talking not only long before the German unification of the mid Nineteenth Century but also well before the simplification of German states that occurred during the Napoleonic period. Consequently:
Up to that time  several dozen independent German States and cities issued their own coinage under their own rulers.
Other common possible choices might have been either the Prussian Thaler or the Bavarian Gulden. The marriage contract was likely denominated in the currency that was kept in hand by the bride's father, as in that way currency exchange would be minimized. If the bride's father was selling property in order to raise the dowry amount, he would have negotiated a currency choice matching that of the expected sale, again to minimize currency exchange.