In RSBot click on the drop down menu 'Debug' at the top.
And click on 'NPCs' so it is then ticked, By doing this it will show you the id
of every monster character etc.
Find your id, use it on the bot then turn the NPCs debug off.
All done
EDIT: The debug is also used for finding lots of other id's for e.g food id's and more,
Useful for other bot scripts.