RMCFIN on a credit report: finance company loan
RMCFIN is probably a loan from a finance company: it runs a name, "RMC", into "FIN", the usual abbreviation for finance or financial.
How to find out which company reported RMCFIN
Your free report at AnnualCreditReport.com shows the full name and address of whoever reported RMCFIN; our guide to identifying a creditor covers the other ways to find out.