OK, I'm going to give a partial try. Basically, RSS is an XML based method, in a fairly specific manner. About the only time I really messed with it myself, was to Export, as XML, for RSS. Which is kind of the opposite of what you want to do. I looked (in my files) and found very little. I did find an XSL file, which would allow you to Import from a RSS source (hopefully). I was able to do so from a XML file, which was gotten from a RSS source.
[ I removed some lines, as they were dupes, and also not very good :-]
The following is what the XSL file (i.e., "file_name.xsl") looks like. It can be put most any reliable where that you can tell it where it is; on your local computer, or on a http place. I cannot be just put in a field, though such could be exported to a known location. XML is fussy about the type of file however, and will squawk if anything is wrong.
I am still working on the Import from many different RSS sources method. It is possible to specify a the "link" connection to different RSS feeds, each a separate Import, but from the same Import script step line. I'll have to find another source first. [ It has been many years since I even looked for such; I used to know more :-|
This is what he XSL looks like. It is not terribly complex, and it should be the same for almost all RSS, as RSS was mean't to be (almost) universal; but likely some do not follow the rules.
<?xml version="1.0" encoding="utf-8" ?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" >
<xsl:output method="xml" encoding="utf-8" indent="yes" />
<PRODUCT BUILD="" NAME="FileMaker Pro XML Import" VERSION="6.0v1" />
<DATABASE DATEFORMAT="yyyy.MM.dd" LAYOUT="" NAME="" RECORDS="" TIMEFORMAT="k:mm:ss" />
<FIELD EMPTYOK="YES" MAXREPEAT="1" NAME="Title" TYPE="TEXT" />
<FIELD EMPTYOK="YES" MAXREPEAT="1" NAME="URL" TYPE="TEXT" />
<FIELD EMPTYOK="YES" MAXREPEAT="1" NAME="Description" TYPE="TEXT" />
<FIELD EMPTYOK="YES" MAXREPEAT="1" NAME="pubDate" TYPE="TEXT" />
<xsl:for-each select="item" >
<xsl:value-of select="position()" />
<ROW MODID="" RECORDID="$c" >
<COL><DATA><xsl:value-of select="title" /></DATA></COL>
<COL><DATA><xsl:value-of select="link" /></DATA></COL>
<COL><DATA><xsl:value-of select="description" /></DATA></COL>
<COL><DATA><xsl:value-of select="pubDate" /></DATA></COL>