It's possible, though it requires a bit of spadework.
There are a number of ways to approach it, including using agents, but I'll illustrate it using a Prototype Rule, adding in this case just the L1 (Link to PDF) data.
(1) You need to create a User variable to hold the data. I'll call it PDF, of type url -- this will make it clickable.
(2) I'll assume you've already got a Reference prototype in your Prototype container -- one is created automatically when you first drag in a Reference. Modify/create the rule for the Reference to:
$ReferenceRIS.contains("L1 - ([^\n]*)\n");
$PDF=$PDF.replace("L1 - ","").replace("\n","")
Make sure the reference rule is not enabled in the prototype, else the PDF KAs will all end up displaying $1 -- this caught me when I was testing the code!
(3) Add the PDF variable as a KA to the Reference prototype.
Existing and new references will now have a link to the PDF file as a clickable KA.
The other variables can be done in a similar fashion.