Support for navigation to C# symbols from F# has been implemented by Vasily Kirichenko and Saul Rennison in our OSS community. The reverse (C# → F#) is something we’re heavily considering for future work.
Phillip Carter, F# PMKen Smith commented
Now that the F# tooling has started to improve, this is probably the main reason that I'm holding back on starting to mix F# into my existing projects. I'd love to play around with F# more, and see if it's really as helpful in a real-world projects as its advocates keep claiming. But I'm simply not going to rewrite everything in F#, and until C# and F# work together more-or-less seamlessly, I just can't give up the quality of the C# dev experience, whatever the values of F# might be as a language.