Which RC? There's a lot of them. Go look on
Erowid.
Research chemicals are a very broad class of chemicals. It's like saying "illegal drugs". The most common ones on blotter these days are probably the 25x-NBOMe series, due to their low cost and low dosage. There are a few others that used to be more common, like Br-DFLY, DOx and 5-MeO-AMT. There are also psychedelics that can be fit into capsules, like the 2c- series and some of the tryptamines.
Everyone responds to them differently. In general, they share qualitative effects with drugs like LSD, mescaline, and psilocybin mushrooms but have their own unique feelings to them as well. None of them are exact mimics of LSD, but some people find them entertaining anyway. They have different durations, different headspaces, etc. You have to do some research before you take them; if you just cram tabs in your mouth expecting them to be like LSD, at best it might be a waste of tabs, and at worst you might be in for a very wild and bumpy ride.
Most importantly, nobody can tell you how RCs look (either in tabs, or as raw powders) or how many tabs are dangerous, because anybody can put whatever amount of chemicals they want onto a tab, pretty much. You have to know the person who made them, or ask someone who has taken them before, usually. You have to know and trust your supplier. There are a few chemical tests you can use to distinguish LSD from research chemicals on blotter, like the Ehrlich / Van Urk reagent. And you can also use UV light - LSD should fluoresce blue, while 25x or DOx will not.
Price discussion is not allowed here either.