Best [Insert row / Remove row] user action for table on touch screen

I have to code a widget displaying a table on a touch screen and I'm wondering what is commonly used to do so? I thought about holding click down between two rows to insert and holding click down on a row to remove it, just like this:

Since it's my first time in the touch screen world, how can I make it intuitive and help the user to "guess" the way he can insert and remove? Because on a regular computer I'd pop some kind of tooltip, if the key stops to move, but touch screens are different because finger is not held when moving.