How to Add File Extensions with Bulk Rename Utility

If you have a set of files which are missing file extensions, and you want to add the same extension to each, you can use this quick fix in Bulk Rename Utility:

In the Regex Match / Replace section on the upper left, enter the regular expression: (.+) in the Match box, and then \1.pdf in the Replace box, assuming you're dealing with files in the PDF format.