
How about HPK in rectangle for Hindrik or Hendrik Pieter Kremer, registered in Groningen 1807- 1832. Born ca. 1767, married to Neeltje van Calcer.
Here are a few examples of the master marks he used. Four times the same master mark to indicate that it was a high-grade silver piece, without town mark of Groningen. Not assayed, sold outside the city of Groningen.
He used the mark HPK in a rectangle, 1807-1812. HPK in a lozenge, during French period 1812 and after till 1816. HP conjoined K under + in square, 1816-1832. Also HP conjoined K, clover in rectangle 1822-1832.
Peter.