i’ve been playing the flute for a couple of years but have not been able to figure out a decent way to key certain notes (particularly f natural & b flat)
casey burns mentions on his site that every note except
e flat can be cross fingered (with a bit of practice!)
anyone know how?!
cheers,
tim 
A lot of this depends on your flute - larger tone holes are harder to crossfinger (they’re usually best half-holed). You need a tuner to check these cross-fingerings to see if they work on your flute, and you often have to lip the note up or down to get it into tune. Don’t be surprised if they sound slightly off or aren’t the greatest on a sustained note. The cross fingerings may also vary with the octave you’re playing in:
Bb = X0X 000 or X0X X00
G# = XX0 X00 or XX0 XX0
Fnat = XXX X0X (but I think half holing Fnat almost always works best)
Eric
I might add here that I sometimes find the cleanest and most in-tune note by cross-fingering and half holing at the same time. With F-nat for example you can experiment with the cross-fingering JayHawk suggested and half holing just a bit at the same time if you find that the note is too sharp. To do this in speed ofcourse is quite difficult. And if you play at speed, people won’t be able to tell if one short note is slightly sharp or flat. Experiment and try finding out what suits you and your flute best.
Bb is very easily half holed.