What's the benefit of paying via RadPad? It seems to be increasing the number of middle men (1. Credit card agency, 2. RadPad), and middleman's commission is often not commensurate to the service provided.
If you were having an emergency putting rent on your credit card could be a short term solution that makes sense. Its better than a payday loan and intro zero percent into APR card could mean you'll only pay 3% in credit card fees. Of course, this is super risky but its good to have that available.