Frieda67 on Ravelry kindly granted me permission to quote her post here. So for those who aren't ravelry members here it is:

"English Version

This post is the english version of the above, how to weave rosepath patterns on a rigid heddle loom with two heddles.

First of all one has to take into account what possibilities there are to thread the warp through the heddles. You can weave as if you have a twill tie-up with 3 shafts.

Back slit - front hole is shaft 1
Back hole - front slit is shaft 2
Back slit - front slit is shaft 3

For weaving you now have the following possibilities:

front heddle up - back heddle neutral is treadle 1
front heddle neutral - back heddle up is treadle 2
front heddle down - back heddle down is treadle 3

Now you can draw the pattern. A simple 3 shaft rosepath would look like this, the picture may make it clearer how the warp runs through both heddles “O” means the thread goes through the hole, “I” means it runs through the slit.

And this is how it looks like, when you also treadle rosepath:

" Frieda67 posted on Ravelry Dec. 4, 2009 in the weben auf deutsch group.