You can add the symbol as an articulation.

If your document was created from the Default Document, then in the Articulation Selection window there is a ready made articulation with the symbol.

In case the ready made articulation is not exactly, as you need it, duplicate the articulation, and edit the duplicate (e. g. adjust the font size, or the default positioning).

It is possible that you, in your Finale document, need to enter this articulation a gazillion times.

To enter the articulation faster, program an articulation metatool for the articulation.

With a programmed metatool you can simply, on the computer keyboard, hold down the programmed metatool key, and drag across the staff.

The articulation will be entered everywhere in the dragged region.

Thank you, Mr. Thomsen.

I think I found it, even though it is put on the note so I have to move it a little bit, but it stays as it is luckily.

Thank you. 

… even though it is put on the note so I have to move it a little bit …

I would edit the articulation’s default positioning so that it automatically positions itself as needed.

And I would definitely program an articulation metatool, and always use that metatool.