The description of Rapid Metamagic (Complete Mage, p. 46):
You possess an uncanny mastery of your magic, enabling you to modify spells on the fly much faster than others can.
When you apply a metamagic feat to a spontaneously cast spell, the spell takes only its normal casting time.
I'll have Arcane Spellsurge up, if my metamagic is all rapid, I won't be able to cast a regular spell + a metamagic one in the same round since the casting time will not be a standard action (from a full round action with the metamagic, so it'll be considered swift from standard) I could however cast a standard spell (from a full round spell + metamagic or not) + 1 standard spell with metamagic or not (to make it swift).
My DM will probably allow it as a house rule but I'd prefer an official rule if there is one.
I know about metamagic specialist + the incantrix class feature that let you do the same thing than rapid metamagic a few times per day.