What you’re trying to do is to have notes added to a Customer Need, correct? Each new note has an extra line space?
I think in that case you might not need to use :append. You can do something like:
Internal Comments = This Customer Need's Internal Comments
AUTOMATED: This need was posted...
Meaning, after the This Customer Need's Internal Comments you need to click on the space after the blue text, hit enter twice, then click on Insert Dynamic Data
If you can’t get around that and you need to use :append, I would do something like:
You view the example here: Rf-lists | Bubble Editor