Step 1 - Create a new custom XML feed
Within your project click on Feeds in the bar on the left side of the screen. You will see an overview where you can select the "+ Add new feed" button.
You will be directed to an overview where you can select the type of feed you want to add. Here, select "Custom XML". The name of your feed will automatically be set to "Custom XML", but you can change it to another name in the name field. When you have select the custom XML feed and given it a name, click the "Continue" button.
The default tags of your feed are set to "item" and "items". If you want to use these tags click the "Continue" button.
However, if you want to use custom tags in your feed you can select the "Custom tags" option and fill in your own tags. The item tag is created for every item within in your feed, and the items tag is created at the beginning of the feed. After setting up your custom tags you can click the "Continue" button.
Step 2 - Setup the categories and rules
For custom feeds it is not mandatory to set up the categories. However, if you do wish to set up categories you can do that in this step and the resulting categories will be Google product categories. You can set up categories using the generate categories function or by manually adding categories.
Step 3 - Setup the finalize
In the finalize step of the feed you will choose which fields you want to add to your feed. You can click on "+Auto-add all fields" to automatically add all the project fields to your feed, or you can click on "+Add new field" to add internal fields one by one.
After adding the fields you can provide them with a channel field name. The channel field name is the tag that will be used for the field in the XML feed.
Step 4 - Activate your feed and get the feed URL
In order to activate the custom XML feed, the project has to be activated as well. Click Settings in the left-hand menu and then choose "activate project". After this navigate to Feeds > Your custom XML feed > Settings and click on the "Activate feed" button.
After activating the project and custom XML feed, navigate to the Preview tab of the feed. Here you will now see the feed URL in the top bar.