How do you call saints to appear?

You do not call the saints to appear. You call them to pray for you before God, since you are not worthy enough to stand by yourself before Him.

CATHOLIC ANSWER History has revealed that there are times when Saints, Mary and even or Lord has appeared to people. This is purely a gift from God to those he wills. Conversing with angels or saints is not a sign of holiness, nor is it praised by the saints before us. "To those much is given, much will be expected." To those that have seen and experienced visions, as many saints have testified by experience, will bear a greater judgment of their actions since their experience should foster greater works of virtue. Often time's saints have encouraged people to ignore such visions if possible. As some have experienced themselves, Satan can often create false visions that can lead many to sin. If one wishes to learn more I encourage the reading of St. Teresa's work "The Interior Castle" Which addresses such experiences. St. Teresa has been declared a doctor of prayer and held up as a great source in dealing with the many degrees of prayer.