Capture all of the screenshots for your presentation using Clarify. Each screenshot will appear in the outline to the left (1).

Click on the Copy image to clipboard button. This will put a copy of the current screenshot along with all of the annotations you have added onto the clipboard.

Now just select Edit > Paste in either PowerPoint or Keynote. Your screenshots will be inserted into your presentation.

Go back to Clarify and repeat the process for each of your screenshots. Once you are done, store the Clarify document in the same location as your presentation. If you ever have to go back and update the screenshots it will be simple to make the modifications in Clarify and paste the screenshots back into your presentation.