Note: You must be an Administrator in order to buy more proposal credits. Credit card billed customer can buy proposal credits immediately. For those few invoiced customers, you'll need to contact customer support so we can work with your accounts payable team.
As an Administrator, go to your Billing page (the drop-down under your name in the top-right corner).
Click on buy credits.
Select Proposals and enter the number of Proposal Credits you want to purchase.
The actual dollar per credit will vary depending upon your plan.
The Account Owner (identified on your billing page) will get a receipt from the purchase.