Just for giggles, let's pretend it was all chance and not actual chemistry.<quoted text>
Assume that the ribozyme is 300 nucleotides long, and that at each position there could be any of four nucleotides present. The chances of that ribozyme assembling are then 4^300, a number so large that it could not possibly happen by chance even once in 13 billion years, the age of the universe.
DNA itself can be any actual length, the length of modern life forms is just what worked best, and they're all not the same length. So basing the chances on any specific length is fallacious to begin with. Okay, but let's go with the 300 one, the chances of it occurring on a gambler's table would be about 4^300 odds for it. But only on the first try, each subsequent try would decrease that chance exponentially, a good way to illustrate that is each try reduces the 300 by one.
Okay, so say that 30 million such reactions occur in a pool of liquid with the proper chemicals every hour. 30 million ... that's probably low balling it. After 300 the chances are reduced to 4:1, that's 400% chance. Tada, you just provided evidence that it not only can happen, but must happen, by chance alone.