This brings up an important topic — how to guide your audience’s reactions.
The first part is clarity of effect. I like to have the audience realize what is about to happen just before it does happen, have a moment to think about the impossibility and then to see the impossible actually happen. This isn’t possible with all effects and doesn’t work well with multiphase effects. Ultimately, the audience should be able to describe the effect in a sentence.
The second part is the building of tension. This is the process through which you lead the audience to understand what the effect is and how it is impossible. The direct way of asking “wouldn’t it be impossible if...?” is not that effective. The better way is to get the audience to ask, “ wouldn’t it be cool if... and then dismiss that idea because it is impossible. You do this through presentation.
The third part is a clear release of tension. The audience needs to know that the effect is over. For some effects it is easy and the audience will react by yelling OMG!, turning away in disbelief or just smiling. For other effects, there is contemplative silence. For multi phase effects you need to convey that you have completed the last phase (and hopefully is is distinct enough and more impossible than the prior phases).
The fourth step is more for parlor and stage performances and that is to give an applause cue. As strange as it sounds, most audiences need to be taught to applaud for magic. If you are using music, the stopping of the music is a cue. A bow by the performer or the performer standing still can be cues. And yeah, sometimes you have to prime the audience or ask for applause (it is a little less obvious if you ask in behalf of the people helping you out as volunteers).
In a PK Touches routine, you should confirm with the formerly blindfolded person that they felt you touch them three or four times and where the felt the touch. Then ask the other person where you touched them. Then explain that there is a secret that the formerly blindfolded person needs to know. “The touches you felt weren’t physical, maybe they were imaginary, maybe they were emotional or maybe they were psychological, do you know why I’m saying that?” Then turn to the other person and ask “how many times did I actually touch [insert name of formerly blindfolded person]?” As they answer “none” pause and look at the formerly blindfolded person to see their reaction. If you look the audience will look and vicariously share the formerly blindfolded persons reaction. After a moment (you want to retain control and not make it uncomfortable), say “I’m going to ask [non-blindfolded person] to escort [blindfolded person] back to her seat and I’m going to ask all of you to give these amazing people a big round of applause.”