For now there’s no way to use substances dynamically. You need to export textures from plugin to regular textures and use them in RTP. But speaking of substance in U2018 - I wasn’t able to use it - crashed - look at my other thread (UBER) where a guy already posted:
UBER - Standard Shader Ultra page-36#post-4153756
I’ll take a look a bit later. Maybe Allegorithmic fix something in meantime so it’s stable for testing.
Tom