If someone comes to a minyan which davens faster then him, is it permitted to START the amidah with them if the person knows he will not be able to respond to kedusha?
Answer:
Yes, this is permitted.
Best wishes.
Sources:
It is not permitted to start later than the congregation if one will not be able to answer Kedusha with them. However, it is permitted to start together with them, even in the knowledge that one will not make it for Kedushah.
Best wishes.
Sources:
See Orach Chaim 109:1 and 109:3.
