Using AJdG Stripe Surcharge
You'll need a copy of Stripe Surcharge to proceed with this guide. You can get the plugin here.
Once you have activated the plugin a new dashboard page appears in the WooCommerce Payments dashboard. You'll see it if you navigate to WooCommerce > Settings > Payments, then click on the sub-page Stripe Surcharge.
You can also reach these settings from the Plugins page by clicking on 'Settings' in the action links.
The plugin is easily configured and only has 4 settings.
The 'Method' setting:
This setting determines what kind of surcharge you'll add. A percentage amount or a fixed amount.
If you know there is always an extra cost of, say, 4 dollars you can simply add that.
If your handling costs change with the order total a percent surcharge makes more sense.
The 'Amount' setting:
The amount is how much you'll charge. If you've chosen the Fixed amount fee, entering 5 will charge $5 extra (or whatever your currency is).
If you've chosen a added percent, entering 5 will add 5% to the total order amount.
The 'Label' setting:
The label is what you'll call the surcharge on checkout and the invoice. Similar to how Tax and shipping fees show up at checkout, the Surcharge will too on a separate line.
If you don't like the word Surcharge, or your country has a different term for it you can change it here.
Sometimes using a term like "handling fee" makes more sense for example.
Subscriptions:
If you want the surcharged applied to subscriptions, check the box for it. This includes the charge on the repeated transactions as well.