rat introductions

ok so Isabelle my little rat is tiny, she was just old enough to leave her mom so she is pretty small, i am looking for a rat friend for her but the one i find are about 6 months old and alot bigger then her. Should i just keep looking and try to find another rat her size or will she be ok with...

I introduced two male rats a while ago, according to the Rat Lady's instructions, but cannot find them to give to a friend of mine who wants to introduce two girls properly. Does anyone have instructions you could send me? I sort of remember them, but want to do it the right way! Thanks...