accordion notation - counter bass note

[Gianmaria Lari]

On the accordion to indicate that a note is to be played in the counter bass we put a small dash under the number of the finger (see attached file capture.png). How can I do it?

* * *

Another convention for counter bass (that my teacher uses) is to put an x in front of the number of the finger. I tried with this code

\version "2.19.60" 

{\clef bass c,_3 d,_"3x" }

but as you can see in the attached file capture2.png the result is not ok because the font size is different. I imagine I can change the font size but I wonder if I'm doing the right things in this way.

Thank you, g.

Capture.PNG
Description: PNG image

Capture2.PNG
Description: PNG image