Adding a new Shortcut in Preferences - the Handbook seems to have it wrong

I would like to add a shortcut to 'Roman Numeral Analysis (RNA)'to the shortcut list in
Edit | Preferences
where it says:
"To create a new shortcut for a command:
1. Select an existing entry in the list.
2. Click Define...; or just double-click the entry.
3. Enter the new shortcut using up to four keys. Press Clear if you need to re-enter the shortcut.
4. Press Replace to change the existing shortcut; or Add, to keep the old shortcut and add the new one."

If I do this, it just adds my choice of Ctrl+Shift+R to the selected "Select to end of bar, Ctrl+Shift+Right"

After some unsuccessful this and the other I stumbled onto it:
In the Search box I entered "Roman" and MU3.6.2 responded "Add Roman numeral analysis" and it let me add the desired shortcut Ctrl+Shift+R - done and tested :o).

I thought I had searched the list of actions without a shortcut but I may have missed the ''Add . . .".