Slide Fit

comfort and what is available. stores tend to not have great selections of slides. my first was a glass Dunlop. I assumed they are all similar and learned how to use it. mine fits loose my my fingers. sometimes the pinky sometimes ring. I hardly focus on how it feels because I am concentrating on where I put it on the strings so much.
of course you dont want a slide that is too tight.
there are more on line sources for slides. some players have huge collections.

ceramic, glass, metal slides all have their own tone.

One trick for a loose slide is to stick a small piece of foam in there to make it fit better (I got skinny fingers too). I actually do that with all my slides because it seems that they never fit "perfectly", and for me it feels like I have better control. To each his own, of course.

Have fun with that slide!

I like loose best. I curve my finger inside to keep the slide on. If it fits out beyond the proximal interphalangeal joint (first knuckle out from the palm), it has to be pretty snug because you can't easily hold it on by crooking the finger. Both ways work. I usually like the slide down against the hand, not halfway down the finger. Too big's not really a problem, but too small is. Lots of slides won't go on my fingers.

My preference is for larger slides with heft. I really love a deep socket that I've had for a few years, it's tungsten steel with a heavily chromed surface; I can only use it for a couple of songs before the weight makes it too hard to use...

One trick for a loose slide is to stick a small piece of foam in there to make it fit better (I got skinny fingers too). I actually do that with all my slides because it seems that they never fit "perfectly", and for me it feels like I have better control. To each his own, of course.

Have fun with that slide!
+1 on that! I use a small piece of door weather stripping, sticky on one side. Works for me. :D