Q. In the Harvard referencing format, do you need to add the page number in the citation when paraphrasing?

Please check the University's referencing page for more details on this. 

If you are a student who started in September 2016 or later, you should include a page number for both direct quotes and paraphrasing.

If you are a continuing student, starting before September 2016, who has chosen to use the 2015 Harvard style, you only include a page number for direct quotes. 

This rule applies to citations in your writing e.g.

Smith (2015, p.3) ...

It does not apply to the full reference as this performs a different function: telling your reader what the source is (book, book chapter, article etc) and giving specific details on how to find it (by following the format specified in the Harvard guide).