First thing to do is to eliminate brake squeak. Pull the front lever on and do your 'normal' bouncing, lifting stuff and see if it is still there. If it has gone you have the answer. If not...
The ball-joints are renowned for failing on the K but I have yet to hear one squeak.
So, to get a little more info, sit astride the bike and ease the front end up and down slowly with the front brake on. Squeaky?
Do it more vigorously. Ditto?
Wheel the bike slowly. Squeaky?
None of this is definitive but it will giive the gurus something to go on. Of course, having a glamourous assistant with a keen ear always helps in these diagnostics.