I'm sorry, I still don't really understand what it is that you're trying to accomplish here... Swiftkey is just a keyboard, it doesn't format text, and although the app you use might allow you to choose the text appearance (again, depends on the app), SMS texting does not support text formatting.
For e-mail, most apps allow you to format the text your sending (with Italics, for instance) because e-mail messages (HTML or Rich Format ones, at least) do support text formatting.