When you open the Main interface, hoover over the page with a mouse in order to Discover your device and click on Customize button. This way you can choose the Profile in the upper right corner where you want to set this option up.
Click on Key Bindings option, choose a key we used key K as an example. See that in the upper right corner instead of FN + K, you choose Key K if you don't want to use FN key combination each time to reproduce this function.
Click Action and in the drop menu choose Open File. In URL to Open filed enter a website or URL that you want to assign. (example https://shop.fnatic.com/)
Click on Save changes. Afterwards you will be able to open the said URL by pressing the assigned key.
If you want to remove the said link from the key, under the Action part choose Default, this will reset it to its basic setting.