Where could I find the Igros K'naos regarding Rambam's works for free online? In particular I am looking for a quote from Radak about the aggados there. A screenshot of that page would suffice.
Text from the 1859 Leipzig edition: http://www.sefaria.org/Iggerot_HaRambam,_Iggeret_Kanaut
As noted by @TamirEvan the Igros K'naos are part of the 1859 Leipzig ed. of Kovetz T'shuvos HaRambam. The quote from Radak can be found on page 3b there.