Using Keyword Suggestions, you can find and add additional keyword ideas for each of your URLs and easily add them to be tracked on PRT.
Enter from left menu: Tools > Keyword Suggestions
Select a URL to get suggestions for at the top, and you'll see the suggested keywords list.
To add keywords, click the Add button at the top/bottom, and you'll be redirected to the Advanced Add, set the wanted tracking settings and save (Add).
Read here more about the Advanced Add.