If you have created custom rendering profiles in Kdenlive, you can share them with the other users. This can be especially useful for example if you created a rendering profile that creates videos for a portable device. In that case, you can browse the list of existing profiles [1] and modify or create a new one [2]. Once a rendering profile is created on the website, it can be automatically installed by all Kdenlive users (requires Kdenlive >= 0.7.3) from the menu "Settings > Install New Profiles...".
Links:
[1] http://kdenlive.org/rendering-profiles
[2] http://kdenlive.org/node/add/render-profile