Sometimes I didn't feel like touching their feet. So I'd try to get away with just a namaste. When my father caught me doing that, he said, "No, no, no. You ought to touch his feet." I'd reluctantly bend down and graze my hands around the person's knees, which was still not as good in my father's eyes. He wanted me to touch the feet, not knees.
But sometimes, I did get away with just saying namaste. It made me feel good. I could blurt it out from where I was, with no foot contact