Secondary professions for a Ritualist

Ritualist Warrior

 * The elite skill Spirit's Strength combined with a Warrior IAS such as Flurry can make a Ritualist melee attacker much more threatening. Be wary of the Ritualist's light armor however.

Ritualist Ranger

 * The Ritualist's primary attribute, Spawning Power can be used to reinforce nature spirits.
 * Serpent's Quickness and Quickening Zephyr can reduce the lengthy recharge times of Binding Rituals without using an elite slot.

Ritualist Monk

 * Ritualists lack hex removal skills, and can benefit from the expanded condition removal from monk skills.
 * Monks Skills are generally more effective on a Primary Monk.
 * Attuned Was Songkai can be used to lower the cost of expensive spells that have quick recharge times for a great effect.

Ritualist Necromancer

 * Spawning Power makes undead allies that have good survivability, but generally have less damage and lower armor due to the lack of Death runes.
 * Explosive Growth is a useful way to add damage when summoning minions, particularly with Animate Bone Minions.
 * Spirit's Gift is also good to use while summoning minions as it will help keep your team alive as well as your minions.
 * Boon of Creation assists greatly with energy management, as it affects minions as well.

Ritualist Mesmer

 * Arcane Echo can be used to increase the damage potential of channeling builds and Ritualist farming with Vengeful Was Khanhei.
 * Mantra of Concentration or Mantra of Resolve can be used to protect against interruption.
 * Mesmers have several cheap anti-Hex skills, such as Revealed Hex, Hex Breaker and Inspired Hex.

Ritualist Elementalist

 * Glyph of Lesser Energy is useful in reducing the cost of your more expensive spells.

Ritualist Assassin

 * A player may not Shadow Step while holding an item. In this way a Ritualist can bomb targets by using a recall skill and forcing the item they are holding to automatically drop.
 * A dagger wielding Ritualist can use Nightmare Weapon for quick health stealing, this will drop your attack dmg however.

Ritualist Paragon

 * This profession combination provides little benefit for a Ritualist primary.

Ritualist Dervish

 * The elite skill Spirit's Strength works well with scythe attacks due to the AoE effect of scythes.