Add rf dynamic script

orchestrallily.ily

@@ -1115,6 +1115,7 @@ hairpinOffset = #(define-music-function (parser location posY) (number?)
   )
 )
 
+rf = #(make-dynamic-script "rf")
 ffz = #(make-dynamic-script "ffz")
 pf = #(make-dynamic-script "pf")
 sempp = #(make-dynamic-script (markup #:line( #:with-dimensions '(0 . 0)