You don't, but you can often make it work the way you need it anyway.
First off, make sure you need to use
RewriteRule instead of simply
ProxyPass. The rule you've provided is quite simple; if you don't have some
RewriteCond logic in front if it, then you can just as easily use
In any case, let's take an example where you're doing something like this:
RewriteRule ^/proxied-location/(.*)$ http://backend/$1 [P]
So, you're taking a request for
http://your-apache-server/proxied-location/something.html and sending it to the backend without the
/proxied-location/ part of the URL.
A redirecting (
30x) response would not include the
/proxied-location/ part of the URL, despite the fact that the client needs that in order to access the other resource through the proxy. That's what
ProxyPassReverse handles. So, just add a configuration like this:
ProxyPassReverse /proxied-location/ http://backend/
The config only applies on requests where the proxy backend handles the response, so the "conditions" that you've applied with
mod_rewrite effectively still apply.