I was trying to get a Reference Dimension (V20) out of DesignModeler, but I don't know how.

(V20) shows the correct displacement to bring a 50 mm radius rod down tangent to a 12 mm thick piece of glass pressed to the mould and will update as R is changed.

The radius of the offset curve is the radius of the mould @R+62 mm, the sum of 50 and 12.

ANSYS 19.1 archive is attached in case you want to play around with it.