There are two Karmapas that can be depicted with both arms extended over the knees. The first is Karma Pakshi. However Karma Pakshi also has the additional characteristic of a small goatee. The second Karmapa who also has with the hands over the knees does not have a beard or goatee.
With some sculpture the cap-like hat may not be rendered in detail, or painted black, which can lead to confusion and an incorrect attribution with one of the Shamarpa or Gyaltsab incarnation teachers.
Jeff Watt 2-2017