The musical term is spelled with an "i"... Ritardando.... often abbreviated as "rit"....
I do all my Rit in BB. It's really easy to go into the measures/bars and edit the beats per measure and the tempo. Once you enter that info into the BB structure, any and all tracks you generate in RB will follow that rit.
When I need to slow down at the very end of the song, I usually do it this way....
Given that: a ritarded ending normally happens in 2 measures of the song..... assuming a 4 beat measure ....and normally at the end.
So I add several measures.... make them all 2 beat measures..essentially, I'm having BB use two 2 beat measures to do what it used to do in one 4 beat measure....... extra measures after the hold allow for a smooth decay of the final held chord.
Now, lets say the song is at 120BPM... the first 2 beat bar is 110, the next is 100, the next is 90, the next is 80. The last note is held so tempo doesn't matter. I'm using 10 BPM as the slope.... you can do more or less to taste.
The steps down are large enough that you can hear and feel the tempo change and the 2 beat measures are short enough, so that it doesn't feel jagged slowing down. You don't want the changes to sound like steps. You want it to sound like a smooth tempo change to the stop.
One of my songs...Dust on the Floor ... uses this method.
http://soundclick.com/share.cfm?id=13017714I've used this same technique in several songs.... you need to experiment to see what size tempo drop works best and sounds smooth. Same thing applies to the beats per measure but I've found that 2 beats at each new slower tempo generally works exceptionally well.
You don't normally want to carry the ritardando out over a longer time frame than just a few measures for it to be effective and sound normal.