Krypton is purely a 2d graphics processing framework. The field of view in krypton simply creates a piece of geometry which is then used to render a texture. As far as what portion of Krypton creates the geometry, you can check out Krypton/Krypton/KryptonRenderHelper.cs
inside the method KryptonRenderHelper.DrawClippedFov(...)
This method takes a field of view, and creates a "field of view" like geometry to render a texture around a specific point, with a color, and size. It *may* be helpful for what you're looking to do.
But, more likely you're looking for either collision detection between a cone and other geometry. For this, you can check out the Farseer Physics Engine (which has some helpful collision detection functions), or Box2D.XNA (which may also be helpful).
Furthermore, if you want a simple way to see if you're looking in the general direction of another point in space, you could simply use a dot product. Vector2.Dot(..., ...) will provide you with a floating point value, which will return a number between
1 and -1, representing "how much" in the direction of one vector another vector is (about the origin of the vectors). You can then retrieve the angle between the two vectors from this dot product.
A dot B = length of A * length of B * cos theta
cos theta = (A dot B) / (length of A * length of B)
or, assuming A and B are unit length, just
cos theta = A dot B
SO, the angle between two vectors is
theta = cosinv((A dot B) / (length of A * length of B))
double angle = Math.Acos(Vector2.Dot(A, B) / (A.Length() * B.Length()));
I hope I understood the question. Please let me know if this is helpful :), if not I'll see what I can do.