Payburner allows you to send XRP to any XRP address or to any PayID with an associated XRP address.  To send XRP, click on the menu icon in the upper right, 

then Send XRP

You will see a form allowing you to enter an XRP address, optionally a destination tag, and an amount of XRP.  Note that the amount is denominated in XRP, and not in XRP drops, which are 1 millionth of an XRP.

You may also send XRP using a PayID.

Complete the form.

and click on Send.  

You will see a progress bar showing the Payburner is sending the payment.

And finally you will see a success message!