The search feature in the MAC viewer is located in the popout on the right.
Mac OS X Sierra search
When you search for a word in Sierra a list will appear in the document on the right as a list, but if you click on a keyword link the Viewer will not jump to it correctly. You have to manually go to each location in the list – i.e. go to the page the keyword is listed on and scroll up/down – to see the highlighted keywords.
This issue will be fixed in a later release of the Safeguard Viewer.