Yes. I have just trained my ds and he will not stand to wee, he insists on sitting on the seat. Even those seats that have a little rise at the front aren't high enough sometimes, so he puts a finger on his wee-wee and points it down the toilet. You could encourage him to stand and wee - my ds will quite happily stand and hold in the shower but not at the toilet. The other option is not to use a potty seat but to hold him over the adult toilet so that his legs are wide apart and gravity will do the rest. Just make sure that you are out of harms way!!!!!
tuck it down if sitting or to watch where he aims it when standing. Ds is 2.7yrs and is a lazy weer he basicaly plonks his tackle over the toilet rim and goes hands free..lol He trained at 2.3yrs and refused to sit down at all to pee so be prepared to have a huge mat under potty while he is learning.