Hi, I had a similar problem. The solution is as follows:
1. draw a rectangle with the outside dimensions
2. select one corner to model the rounding
3. draw a two horizontal lines parallel to the short side
a) first is 7.35mm from top edge
b) second is 11.60mm from top edge
4. draw a vertical line at 9.28mm from side edge
5. make an ark starting at intersection point of top edge and line from (4) and ending at first horizontal line (3a)
6. make an ark starting at ending point of previous point and intersection of side edge and 11.60 line (3b)
7. make first ark tangent to top edge
8. make first ark tangent to second ark
9. make second ark tangent to side edge
That should be all.

Image 1: a finished sketched of the described geometry.