Depending on the type of ChemRICH analysis you are computing, you may need to obtain PubChem Identifier, KEGG ID, SMILES codes or InChiKeys for your data-set.
You can use this curated Excel File to get some of these identifiers (LINK). For compounds that still don't have these identifiers, you must use the PubChem Identifier Exchange Service to get IDs. It is strongly recommended that you are using the PubChem service to get the SMILES codes and other identifiers because identifiers provided by any other tools may be outdated and may have broken SMILES codes.
PubChem Identifiers Exchange Service is available here : https://pubchem.ncbi.nlm.nih.gov/idexchange/idexchange.cgi
Below is the embedded page of the ID exchange service and you can use it directly here.