This is mine, make of it what you will - take it, ignore, disagree!
'Thanks for doing this for me. Own left back, help me out with in/out of play - throw ins, corners & goal kicks. Nice clear signals please. Most of the time I will go with you, but I may overrule if I see something that you haven't - happy to talk about it afterwards. Offsides - we could be here all day, so will keep it simple - I only want a flag if ball is near the offside player or he plays it. If ball on one side of the field, player on the other then I don't want offside. When you raise your flag, I will do 3 things, blow my whistle (obviously) which I will do most of the time, if I disagree I will raise my hand, please put flag down - again happy to discuss afterwards - if I miss you, do give me a shout. Leave anything else - fouls, foul throws, misconduct to me. If anyone says anything to you, let me know & I'll have a word with them. Thanks for doing this for me.'