What are the strengths and weaknesses of Rido saddles? I've started riding more often now (big plus), and as a result am getting, ahem, saddle issues with my classic San Marco Rolls saddle. I'm an average build, 5' 8-9". The saddle issues are mainly chafing at the top of my legs, some more serious skin damage, and general soreness.

I've heard good things about Rido saddles. Specifically that they transfer the weight from the perineum to the assbones which are better built for weight distribution. 

What are these saddles best and worst at? Are they good for particular types of riding, or riders with particular builds? Are they good for particular kinds of bikes? I ride a Batavus Pro Team road bike circa 1990 which is about right size for me.

Is there anything specific to this saddle that has to be taken into account, position of saddle fore and aft, angle of saddle, or position of handle-bar stem, etc?
Yes, I think a Rido is worth trying in your situation. Of course, make sure your bike fits you properly, saddle height and tilt are properly adjusted, and so on. 

I found my Rido saddle to be good for riding with padded shorts, but not so comfortable with street clothes. The saddles seem to be designed for moderate distance riding in a sporty position. 



Of course, the only way to tell if this saddle will work for you will be to try it, but I think that a saddle like the one I had (see the picture) may work for you. When I rode the pictured bike for rides of half an hour to 45 minutes, the Rido took care of my chafing issues (the same as the ones you're having), since the saddle's nose is fairly narrow. When I replaced that bike with a Bike Friday and a Brooks, I replaced the Rido with the original saddle and turned this bike into a city pootling bike.