Which high risk strains of hpv would cause flat warts on hands and top of feet? i didn't think they did but wanted to ask?

First, don't assume you have warts at all, unless a doctor has confirmed that diagnosis. Most flat spots on the skin are not warts and not caused by HPV. If a doctor (preferably a dermatologist) confirms warts, the most likely type causing such an infection would be HPV1, the cause of common skin warts, plantar warts, etc. Probably not any sexually transmitted HPV type.

Get HPV vaccine to prevent infection with cancer causing strains of HPV. The strains causing warts are usually not high risk infections.