KeyTagger
Opening KeyTagger pane
Typing out the same tags over and over again is tedious, not to mention unnecessary. using the KeyTagger feature, you can assign 12 commonly used tags to the hotkeys F1 through F12 on your keyboard. Click "KeyTagger" in the main sidepanel, or select it in the first dropdown menu top-left in the window.
Configuring KeyTagger
The dropdown menus are where the tags should be written, eg. Rating or Tags-General. Between the dropdown menus are textfields where you enter the tag itself. Simply fill in the information as you wish, and click the checkbox at the top to enable the feature.
Using KeyTagger
While you are browsing images in fullscreen mode, just hit F1 -> F12 to tag it with the appropriate tag.