In Biab RealDrums are limited to 2 bar endings, with EZDrummer Jamstix you can create custom endings for RealDrums. If you don't have these, tho there is a free version of Jamstix, you can use the Playable RealDrums and just drop the midi ending in.

Watch: https://www.dropbox.com/s/fzq59yc6lfdcqqr/BB23-4-Bar-Endings-Drums-EZDrummer.mp4?dl=0