Edit: At first, I was looking for a way to add natural signs manually. Turns out that, at least for the moment, I actually need to place accidentals manually. Generally, I might need both in the future.
There's another question on how to create custom key signatures in Lilypond for Turkish folk music.
I'm using the code from the selected answer posted there to create a combination of ♭ and ♯ with additional superscripts. This allows me to write
f in Lilypond code for the 'microtone' note that's between f and f♯. But now I need to use both this note (which is not on the piano) and f♯ (black key on the piano).
I'd like to simply set a ♯ manually in front of some f's. Is there a way to do so? Or any alternative approach?
To clarify: Lilyponds treats the score as if it was a mixture of F major and G major, so it sets a ♮ in front of each b and f automatically, but nothing in front of bes or fis.