I will pay back 0.063 BTC in 2 weeks
If you require collateral
I will send you ~139 RIC (Riecoin) as collateral which are worth 0.064 BTC at current buy order.
I know, it's small
You obviously just want to sell the Riecoin.
Why can't you sell it yourself right now for 0.064btc? You'll get more than you're asking for here, and you won't owe anyone anything.