The primary means of financing the International Monetary Fund is through members' quotas. Each member of the IMF is assigned a quota, part of which is payable in SDRs or specified usable currencies ("reserve assets"), and part in the member's own currency. The difference between a member's quota and the IMF's holdings of its currency is a country's Reserve Tranche Position (RTP). Reserve Tranche Position is accounted among a country's foreign-exchange reserves.
References
Reserve Tranche Position Wikipedia(Text) CC BY-SA