Adobe Typekit is an online library of fonts. To use Typekit fonts with Oxygen, you must have a Typekit account.
You can connect Oxygen to your Typekit account from the Oxygen -> Typekit page of your WordPress admin panel.
Generating a Typekit API Token
Login to your Typekit account.
Click your Account Avatar at the top right, then click API Tokens.
Click Make me a new API token to add a token.
Copy the API token.
Connecting Oxygen to Typekit
Go to Oxygen -> Typekit in your WordPress admin panel.
Paste in the API token and click Submit.
Select the kit you want to use with Oxygen, and click Submit again. Your domain name is automatically added to this kit. Note that it may take up to 5 minutes for Typekit's servers to update and the fonts to be available for use with Oxygen.
The fonts in this kit will now be available on all of Oxygen's Font Family dropdown lists.
Creating a Kit on Typekit
Once you are logged into your Typekit account, you need to choose the fonts you wish to use with Oxygen by adding them to a kit.
First, click Kits > Create new kit at the top right.
Then, type a name for the kit. You may also specify the domain it will be used on, though this is not necessary.
Click Continue twice, and then click Browse All Fonts.
Once you've found a font you wish to add to the kit, browse to the font page and click Add to Kit.
Then, select the kit from the list and click Publish.
Repeat these steps to add additional fonts to the kit.