I assume you mean that you have some URLs and you want to turn them into an RSS feed?
If that's the case then there is the proper way of doing it and then there is the dirty and quick way of doing it.
I did this before and what I did was just create one from scratch. Here is how.
1) I created a file named feed.php
2) I found an existing Rss2.0 feed and replaced everything that could be made into a variable, such as the feed title, feed link, etc.
3) I pasted the changed file in and added php to echo the variables into the places where they need to appear.
4) for the item enclosures, I put them into a loop and looped through a list of urls. That list of URLs could be a txt file or CSV, if you wanted.
In the end, I put the php file up on my server and the output validated. I call this the quick and dirty way. I am sure there are other better ways to do it, but mine worked for me.