The macro $user_ip expands to logged-in user's IP address:
client_out = "{ ssh, domain, pop3, auth, nntp, http, https }"
udp_services = "{ domain, ntp }"
pass quick inet proto { tcp, udp } from $user_ip to any \
port $udp_services
pass inet proto tcp from $user_ip to any port $client_out