сам же и отвечаю:
FAQ: How do I insert a line break instead of a paragraph?
Using the Enter key inserts a paragraph (<p>, <hx> or <pre>). Using shift-Enter will insert a line break (<br />).
You may also disable RTE Page TSConfig property EnterParagraphs. Then, Mozilla/Firefox browsers will behave in their native mode and pressing the Enter key will insert a br tag. However, Internet Explorer will continue to insert paragraphs on pressing the Enter key.
надо мануали сперва читать
