Please click the image for watching Attaching Image in Card Using Copy and Paste in Restyaboard.
  1. Goto any one of the board in your Restyaboard.
  2. Click any one card in the lists.
  3. Please open the image with imageviewer (or) the browser and click copy and paste the image path in the comment section of the card and the attachment will be shown in the attachment section of the card.