Thank you OxFE (Mohit), you save my life !!!
I had read a non-exhaustive tutorial in vextab/doc/tutorial.html
I had not seen this feature to indicate the number of notes in a tuplet.
Is there anywhere an exhaustive document that indicates this kind of functionality ?
So i have an another problem, perhaps i must create another discussion about ?
here i got this rendering

With this vextab code
options space=50 font-face=petalumaScript
tabstave notation=true tablature=false key=C clef=treble time=4/4
notes :8 ## A/4 :8 tA/4 G/4 F/4 ^3^ :h t F/4 :q B/4 ^3,2^
the 8th A after the 8th REST have a beam, how can i get a single 8th for A ?