Thank you for your question about fertilizing your hibiscus plant.  The University of Minnesota Extension tell us:

• Hibiscus are heavy feeders and require a balanced fertilizer such as 20-20-20 or 10-10-10.
  • Use at half the label recommended strength every 2-3 weeks when placed outside for the summer.
• Indoors, fertilize less often, using ½-strength formulation, every month or so in spring and summer, less frequently in winter.

We are not able to recommend brands, but if you check the label and look for the 20-20-20 or 10-10-10, which means Nitrogen (N) - Phosphorus (P) -  Potassium (K), the mix has you will be good.  Make sure to follow the instructions about amount to use, and then use at half that amount every two or three weeks until about mid-summer.

Here is a link to the UME publication, which gives many good growing tips for hibiscus.
https://extension.umn.edu/houseplants/hibiscus#fertilizing-1440064

Best of luck with your hibiscus.