At this time, we are only able to process donations to non-US charitable organizations that have a US 501(c)(3) status from the IRS, or the select international charities shown here. For instance, the Canadian Cancer Society has received 501c3 status from the IRS, so we are able to process donations to them.
If an organization isn't already in our database (search here), you can check and see if they have 501(c)(3) status by checking either ProPublica's Nonprofit Explorer or IRS Exempt Organization Select Check. You can get the US-registered nonprofit added to our database by following the instructions in this article.
We are working on expanding our international donations reach and will update our community when we have added that capability.