\version "2.19.15"

meTrans =
#(define-music-function (parser location mus txt) (ly:music? string?)
   #{
     \transpose c cis $mus \rightHandFinger \markup\normal-text\bold\fontsize #0 $txt
   #}
   )


  {
  \transpose c cis c' \rightHandFinger \markup\normal-text\bold\fontsize #0 "A"
  \meTrans c' "a"
  }