How should I romanise [ɸ]?

So my language Kiyourmic uses the following phonology:

https://preview.redd.it/mycldtapr8ce1.png?width=553&format=png&auto=webp&s=394b46c62967d5aec085db0ff81dea4a6edec761

I currently use <ɸ> to romanise [ɸ], but I am not sure if that is the best option. I chose this because I hugely dislike the way <f> looks in some words. Might just be because I associate it with some words in my mother tongue (Dutch) and words in English too.
Does any of you have some advice or ideas on how to approach this? Digraphs are fine as long as it's not basic <ph>.

If you have any other advice or questions in terms of phonology or orthography please tell me.

Thanks in advance!!