Install it first:

$ gem install rultor

Run it locally and read its output:

$ rultor --help

To encrypt one file for Rultor:

$ rultor encrypt -p yegor256/rultor secret.txt

Where yegor256/rultor is the name of your Github project and secret.txt is the file you need to encrypt. Result will be saved into secret.txt.asc. Read more about Rultor decrypt configuration option.

Make sure you have gpg and bcrypt installed on your machine (only Unix or Mac OS at the moment).