The Collaborative International Dictionary of English v.0.48:

Ryder \Ry"der\, n.
   1. A clause added to a document; a rider. See Rider. [Obs.]
      [1913 Webster]

   2. [D. rijder, properly, a rider.] A gold coin of Zealand
      [Netherlands] equal to 14 florins, about $5.60 (ca. 1910).
      [1913 Webster]