Check in the Jepp Airport Directory. In the first pages they provide ACNs for all A/C. At the end you will find national register of all the airports in the country. The register info includes the RFF cat and LCN. I don't have it in front of me be but most are classified as "u" unknown in the DRC. I don't even think that there has been an AIP in many years so the information available should be taken with a pinch of salt. Good luck