The Occultist archetype of the Arcanist has a spell-like ability
Conjurer's Focus (Sp)
An occultist can spend 1 point from her arcane reservoir to cast summon monster I. She can cast this spell as a standard action and the summoned creatures remain for 1 minute per level (instead of 1 round per level). At 3rd level and every 2 levels thereafter, the power of this ability increases by one spell level, allowing her to summon more powerful creatures (to a maximum of summon monster IX at 17th level), at the cost of an additional point from her arcane spell reserve per spell level. An occultist cannot have more than one summon monster spell active in this way at one time. If this ability is used again, any existing summon monster immediately ends.
Metamagic and metamagic wands can not be used with spell-like abilities. However, it reads to me that the spell-like ability here is not the spell "summon monster", but the ability to cast the spell in a certain way, with certain benefits. If "summon monster" is not a spell-like ability in this case, should metamagic be allowed?
Metamagic that alters spell slots that would need interpreting, but metamagic rods don't have that issue.
No, it's still an SLA.