I have a part, that has two arcs at the end of a board. I want to create a linear dimension of the overall length of the part. I expected to be able to select the two arcs, and then later edit the dimension to show the max dimension. However, when I try to select the 2nd arc, I get the message that a dimension cannot be created between them. (see the attached screen grab). I've also attached a sample part and a drawing of it, where I want to create that overall length dimension.

I've tried creating a sketch with points on the middled of the arcs, and also adding horizontal lines. But, those didn't work either. I've tried editing the radius dimension that it created so it will show a linear dimension of the diameter. But, I can't edit the dimension to move the dimension line to the side when I try that. Also, note that I need to eventually rotate this view so it is shown horizontally on the paper (there will be another 15 or so, part views added eventually). I 

How do you recommend that I create such a dimension?