When you install packages (programs) from the install cd's, you will notice that you get prompted to switch disks to disk #2...
Each package that you install, such as Amaya, may have other packages or libraries that it depends on.
Using rpmDrake, or whatever the package installer is in Mandrake (I got so many, I can't keep track), you notice that it may want to install more support packages than the original package that you picked.
This is called a dependency. Amaya depends on other packages to work.
When you install a package, like Amaya, independent from the auto-install feature in Mandrake (that installs and attempts to meet the dependencies for you), the same thing happens. But, you need to know what other packages are needed to make Amaya work properly.
If you don't, rpmfind is a web based rpm repository that can help to sort this out, to some extent.
When you get the message trying to install Amaya, that a dependency is not met (as you did), then Mandrake tries to tell you what is missing.
The resultant message does not always make sense to the average user.
So, if you go to the link that I provided, that shows the Amaya package, and scroll down to the dependency section, chances are that you can ID the missing library package, in your case librdf.so.0.
Click on that and hopefully you find an rpm package, for Mandrake, that meets that dependency.
Amaya may depend on other packages, as well.
That's when folks call this dependency hell!