I'm Russian and "Как вы на это увидел" is not correct. In fact, I don't even know what that's supposed to mean, sorry. "Как вы на это смотрите" on the other hand is perfectly normal and basically means "What do you think of that".
"Он предложил это. Как вы на это смотрели?" could be literally translated as "He proposed that. How did you see (or look at) that?", but the correct translation would be "He proposed that. What did you think about that?".
Source: am a native speaker.