The Silkies might never perch. I have had them at various times over 40 years and have just bought a pair of May hatched ones. I'm looking for 2 more unrelated pullets. I think the extra toe is a hindrance to gripping a perch.
The R.I.R's should perch, but might take a bit of persuasion. When you have replaced them on the perch for the umpteenth time you start to feel like supergluing them in place. 2 is not too bad, but I had 12 to teach, and as fast as one settled down, another fell or jumped off. I have a couple of Solar Lamps which charge outside all day, and I pop in the house at night to give a few more hours of light to keep them laying through the winter. That also serves the purpose of letting them see where the perches are. Once a couple start to perch, the rest follow suit.