Are you saying that the two points are not aligned with (either 'on' or parallel to) the "angled edge"? Because if they are, use the 'Point-to-Point' method.
First, use the Linear Dimension command. Then, in the Measurement group, set the Method to Point-to-Point. When you do this, a Use Measurement Direction option becomes available. When you set this option, you can then click the Specifiy Vector button to specify the direction of measurement (which in this case would be your angled edge).
Thanks for the . I spent a lot of time to activating the views and drawing lines thru the points, perpendicular to the edge to show the dimensions.
Rapid Dimensions have most of the options/methods in the Dimension dropdown box. I hope in the next releases NX will centralize the cluttered options/methods and clean and delete the duplicates to avoid this kind of situations.