Google Sites automatically adds rel="nofollow" to all external links. There is no way to override or remove this - Google Support Post.
Internal links (links to pages within your own site) are no affected by this - you can add rel="me" to internal links and it won't be stripped out / replaced.
In Google sites it's not possible to upload your own HTML or view any of the FTP tree the only way to edit/create pages is through the built in editor . But there are many alternatives out there. I'd recommend 000webhost for a free web host. I use it for my file servers and have used it for forum sites in the past. But there are tons of services out there that can do exactly what you need to do. Just not under the Google name.
The reason Google disallows such free editing is because they want to avoid any kind of phishing sites and such out of their domain.
Best Answer
My first attempt to Google on this topic yielded in a first hit: search result LATEX Google Sites.
On the following two websites, it is explained how to show the LATEX on Google Sites:
See snapshot of last reference: