Yes, with conditions. RRF funds may be used to make regularly scheduled payments for any business debt (both principal and interest). This does not include any prepayment of principal or interest, including for a PPP or EIDL loan.
This means that if the recipient has a PPP or EIDL loan that must be repaid, the recipient may use RRF funds to make the regularly scheduled principal and interest payments for the PPP or EIDL loan. For example, because most PPP loans have a 5 year repayment schedule, the recipient may use RRF funds to make the regularly scheduled monthly payments over the length of time that the recipient is using its RRF funds - recipients may not prepay the entire PPP or EIDL loan.