Multiple WAN

o i want to use “4 ip WAN,Load Balance” to one computer and “1 ip WAN” for others.
This is how i guess i have to do it.
Internet (5ip dhcp) 1tp cabel → “WAN switch” → 4tp cabels → RB750gl → comp(4ip)
1tp cabel → Dlink-855 → Others

Is it possible to use only RB750 to do this, or do i need the switch?
Ie 1WAN port(5ip) → 4ports for LAN
WAN ip are not STATIC. only dhcp

There are multiple ways to do it. Look in the wiki for very detailed examples. After you do that, ask more specific questions here.