Yes you can use only SPF with DMARC, however this greatly reduces deliverability.
DMARC relies on (aligned) authenticated identifiers from both SPF and DKIM, if one fails but the other passes then DMARC will pass. Using both SPF and DKIM increases the chances of emails being delivered. Further SPF does not survive forwarding of emails which means that DMARC will always fail if only SPF is used and the email is forwarded. Therefore DKIM should also be implemented as it survives forwarding and DMARC will pass.
Most email providers support both SPF and DKIM and there should be no reason why only one should be used.
To learn more about Identifier Alignment please click on the button below.
If you would like to further explore DMARC please click the button below.