When reading Raamkali kee vaar, I don't understand this line, especially the words
ਫੇਰਾਈਐ and ਖਟੀਐ. If someone could translate these words for me and write the meanings for this line, i would be grateful.

This pankiti is from the second pauri of Tikke kee Vaar also called Ramkali kee Vaar and also called Satte Balwand kee Vaar. This Vaar was uttered by hazoori Kirtanis of Guru Arjun Sahib jee - Rai Balwand and Satta Doom. In this pauri they talk about the greatness of Siri Guru Angad Dev jee.

In this particular pankiti, they talk about the time when Siri Angad Dev jee was made Guru by Siri Guru Nanak Dev jee. The pankiti in question talks about how glory of Guru Angad Dev jee pervaded the world because of glory earned by Guru Nanak Dev jee. In other words, Siri Guru Angad Dev jee fed on the glory earned by Siri Guru Nanak Dev jee:

ਲਹਣੇ ਦੀ ਫੇਰਾਈਐ ਨਾਨਕਾ ਦੋਹੀ ਖਟੀਐ ॥

ਫੇਰਾਈਐ ਦਾ ਮਤਲਬੇ ਹੈ ਫਿਰ ਗਈ। ਕੀ ਫਿਰ ਗਈ? ਦੋਹੀ (ਵਡਿਆਈ) ਫਿਰ ਗਈ। ਕਿਵੇਂ ਫਿਰੀ ਇਹ ਦੋਹੀ? ਗੁਰੂ ਨਾਨਕ ਸਾਹਿਬ ਦੀ ਦੋਹੀ (ਵਡਿਆਈ) ਖਟੀ ਦੇ ਸਿਰ ਤੇ।

ਖਟੀਐ ਦਾ ਭਾਵ ਹੈ ਖਟੀ ਕਰਕੇ, ਜਾਂ ਬਰਕਤ ਕਾਰਨ।

Daas,
Kulbir Singh

makes sense. thanks.