We can load the model by pointing using the ID to an that specifies the src to a file:
<a-scene>
<a-assets>
<!-- At first we load skeletal animation blending JSON as asset -->
<a-asset-item id="hand" src="/?originalUrl=https%3A%2F%2Friptutorial.com%2F%26quot%3B%2Fpath%2Fto%2Fhand.json%26quot%3B%26gt%3B%26lt%3B%2Fa-asset-item%26gt%3B%2520%2520%26lt%3B%2Fa-assets%26gt%3B%2520%2520%26lt%3B!--%2520Now%2520we%2520can%2520use%2520that%2520asset%2520with%2520blend-model--%26gt%3B%2520%2520%26lt%3Ba-entity%2520blend-model%3D%26quot%3B%23hand%26quot%3B%26gt%3B%26lt%3B%2Fa-entity%26gt%3B%26lt%3B%2Fa-scene%26gt%3B%253C%2Fcode">