Non US-citizens cannot directly or indirectly donate to a US federal election campaign -- only US citizens and permanent residents ("green card" holders). It is also illegal for you to solicit donations from non-US citizens.
Donating to a US-based Ron Paul ChipIn is indirectly funding a campaign. Is it worth getting the official campaign in hot water?
Official info here: http://www.fec.gov/pages/brochures/foreign.shtml