From the release you wish to use: https://github.com/dzbarsky/rules_rs/releases copy the WORKSPACE snippet into your WORKSPACE file.

To use a commit rather than a release, you can point at any SHA of the repo.

For example to use commit abc123:

1. Replace url = "https://github.com/dzbarsky/rules_rs/releases/download/v0.1.0/rules_rs-v0.1.0.tar.gz" with a GitHub-provided source archive like url = "https://github.com/dzbarsky/rules_rs/archive/abc123.tar.gz"
2. Replace strip_prefix = "rules_rs-0.1.0" with strip_prefix = "rules_rs-abc123"
3. Update the sha256. The easiest way to do this is to comment out the line, then Bazel will print a message with the correct value. Note that GitHub source archives don't have a strong guarantee on the sha256 stability, see https://github.blog/2023-02-21-update-on-the-future-stability-of-source-code-archives-and-hashes/