RFCs are relatively easy to find on the Internet. Many companies and educational institutions maintain complete local repositories of RFCs, so you should check for such a local repository that may be convenient to you.
When the IETF announces an RFC, primary English RFC repositories already have the RFC. The following URLs are paths to primary repository directories. The English versions are authoritative. Their directories have a file for each RFC with a file name of the form “rfcnnnn.txt: without leading zeros—for example, rfc2821.txt or rfc792.txt. If the file is also available in Postscript or PDF, a version of the file will exist with a “.ps” or “.pdf” suffix.