It’s my experience that when I wish to add a new site to Newsblur, I first copy the URL of the feed or site desired, open the New Site dialog, then paste the URL from the clipboard, rather than typing the URL by hand.
It would be nice if when opening the New Site dialog, the dialog read the clipboard and filled the URL field with the contents. It may be necessary for some form of error-checking to ensure the URL is validly formatted.