What are some examples of Romanticism in Frankenstein, chapter 5?

Romantic literature often focused on individualism, emotion, and a tortured hero who has broken the rules of society, God, or nature.
In chapter 5, Romanticism is expressed through the intense emotions of anguish and disgust Victor experiences upon seeing his creation. This sense of horror overwhelms him. As he puts it:

Sometimes my pulse beat so quickly and hardly that I felt the palpitation of every artery; at others, I nearly sank to the ground through languor and extreme weakness.

Shelley shows how deeply Victor feels the pain of having created a monster. His response is not rational, reasoned "what do I do now?" but a severe emotional reaction of distress.
Second, the chapter shows Victor, the isolated individual genius who has worked alone in his tower for several years to create life from inanimate parts, as the tortured hero. Like Prometheus, who was punished for taking on the privileges of the gods in giving fire to the humans, so has Victor overreached his human bounds. This is a very typical thing for a Romantic hero to do: such a hero often attempts to do more than mere mortals can achieve. Victor is punished and tormented for taking on the prerogative or privilege of God in creating human life.
Shelley also points specifically to Victor as a Romantic figure being punished for violating God's laws by quoting in this chapter from "The Rime of the Ancient Mariner," another Romantic work in which the protagonist, the Ancient Mariner, is punished for violating the laws of God and nature.