Problem. The SDK team hasn't touched the Scene_Battle scripts as yet, so... um...
Best bet is this. Post the SDK v1.5 script first, then paste RTAB below it. Believe it or not, it is compliant enought that RTAB will work with the SDK MAIN script above it. That's not saying that RTAB will not overwrite some things, but what it doesn't overwrite will allow SDK-Using scripts to run.
Dunno which SDK-Using scripts will or won't work... not completely, but I have run a few with RTAB.