To add additional data such as a user id, you need to add the "Website data" element in our feedback form builder, and link this field to the javascript, html element, url parameter or cookie where your web page data is stored. To apply this, please read the description below:
Step 1
Go to 'Data collection' at the top bar and click on 'Feedback forms'.

Step 2

Now you will see a screen with feedback forms, if it's already created. Now click on the 'Pencil' button to edit your feedback form.
Step 3

Now you're in our form builder. You can add additional data by adding an element called "Website data". In the options section of this form element you can connect them to the variables on your page. Just click on the 'Website data' line to connect your variables.

Step 4

In case you want to use a JS variable, the variable should be globally accessible, so for instance if user_id is a global variable it will take the value it contains and pass it along as feedback (as a string). The variable can also be an object or array or even a nested object (for instance: test_object.user_id), if the value of the specified variable is an array or object it will be encoded into a JSON string. Basically as long as the variable's scope is global we'll be able to pick it up.
For the CSS selector option you can use a tag, a class, an id or an attribute. If you want to use a class make sure to start with a dot like this: .my-class. If you want to use an id you should use a hash like this: #my-id. It will add the entire element where the class, id, atribute or tag is available.
If you want to collect the url parameter, choose the url parameter option and use the name of the parameter. Once added this will collect the value of the parameter.
The cookie option works similar to the previous options. Just use the cookie name and the value will be added to the website data in your feedback results.
Step 5

Don't forget to save your feedback form by clicking on the green 'save' button.
Step 6

Your additional Website data will be added to the feedback as soon as feedback is submitted by your website visitor.
The Website data will be available in the Feedback results section (Dashboards / Feedback results).
Note: you can also use these variables in your chart builder to combine your additional website data with other feedback elements such as an NPS or Customer Satisfaction score.

Now your able to add additional data to a feedback result!