This is automatically done when scanning an item with an AR scene created with the Creator. For this, you need to create an AR Item in craftAR instead of an Image Recongition Only Item. Then you can add images, videos or 3D models to your AR scene. The SDK automatically loads the AR contents and renders them on top of the image.
The creator will fill in the ‘contents’ field inside the AR item. This will be received by the SDK and parsed to load all the resources for the AR scene. Note that the custom field is intended to add additional information but is not where the AR scene is stored.