There are a few ways to do this but you probably don't have to use reverse proxy unless your keen on having the projects on different ports/host names and don't want the user to know. Other wise just use Alias
If using mod_proxy you would want to put the reverseproxy directives in a www.example.com vhost entry, you could also specify a document root for it. Then setup more vhosts for each of your projects, e.g. one.example.com. Each vhost can have a different DocumentRoot specified. Note you could accomplish something similar to reverseproxy via Redirect permanent however this would require a dns being setup for the subdomains. With your mod_proxy solution you can just add the subdomains to the hosts file.
Use one of the methods mentioned here: https://httpd.apache.org/docs/1.3/urlmapping.html Alias directive, ScriptAliasMatch, User Directories with AliasMatch