K@f1
I assuming you mean Kf1.
B 1.g6-f5 killing the f6 pawn (en passent)
( if this move is not legal do let me know. As far as I know this move should be a legal one)
No, en passant only works if I move 2 squares. Since the piece was just placed on f6, and it was never on f5 it never passed f5 for you to take there.
Chessy and pawn slayer are right; the move is illegal.
From the chess.com chess tules and basics page:
"
The last rule about pawns is called “en passant,” which is French basically means “in passing”. If a pawn moves out two squares on its first move, and by doing so lands to the side of an opponent’s pawn (effectively jumping past the other pawn’s ability to capture it), that other pawn has the option of capturing the first pawn as it passes by. This special move must be done immediately after the first pawn has moved past, otherwise the option to capture it is no longer available. Click through the example below to better understand this odd, but important rule.
"
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B 15. Qh4+