While you can model forks in BikeCAD, BikeCAD is not really setup for generating all the dimensions you may want for building the forks. I'm not sure what you mean by the angle between the fork blades and the steerer. When you use a curved fork blade, BikeCAD assumes the fork blades will be parallel to the steerer tube at the top. If you use straight blades, BikeCAD does connect the blade to the steerer tube at an angle. By default, the fork looks to be made of carbon, so its a little ambiguous where that angle should be measured from. However, you could use your own judgment to create a user dimension for the angle as shown below.

If you were envisioning this angle to be something measured when looking at the fork from the front, BikeCAD doesn't generate dimensions for this view either, but again, you could create one with a user dimension.