Select the Insert section then select More Gadgets.
Find and open the Insert menu in the Google Sites Editor. You will see a list of components you can embed on your site, like Tables, Images, and Links. Find the More Gadgets option, and click it. This allows you to install customizable tools such as the POWr Tumblr Feed to your site.
The Gadget manager will be visible. Select Add Gadget by URL. Then copy and paste this exact URL into the box. Choose Add to complete.
Now that you've added your new, editable Tumblr Feed Widget to your Google Sites page, you might want to resize the Widget. Using the options in the pop-up, pick a height and width for your plugin. You can also choose to add a border, scrollbar, or title around your Tumblr Feed Widget, but we don’t recommend it. You will have more editing options through the plugin.
Set up POWr Tumblr Feed
Visit the live Google Sites web page and select the Settings Icon in the top right corner of the Tumblr Feed Widget.
In the POWr Editor, click Import Existing Tumblr Feed, find Tumblr Feed- and click Copy.