How do I enter a line feed or carriage return in dictation.

"new line"

FYI: -> http://blog.crushapps.com/2011/10/more-fun-with-siri-dictation/

It depends on what computer you're using. On a Macbook pro press the option key and return.

Since this was posted in the iPad forum 4 years ago, I would guess they were using an iPad at that time.