The flow is simple, when there is a text box / area (not just a regular textfield). Have a small button in the top right corner. when you tap it, it shows you a placeholder in the form saying "what do you want to say?" or something similar (use laws of ux). You type in what you want to say, for example, "write a concise, 2 sentence max, about working at Apple". This reminds me, this should be where we also have the context of the text area, in the last example, it may have been "Describe your best job experience".